Unihemispheric slow-wave sleep

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https://en.wikipedia.org/wiki/Unihemispheric_slow-wave_sleep

A young House Sparrow (Passer domesticus) exhibits Unihemispheric slow-wave sleep.

Unihemispheric slow-wave sleep (USWS) is sleep where one half of the brain rests while the other half remains alert. This is in contrast to normal sleep where both eyes are shut and both halves of the brain show unconsciousness. In USWS, also known as asymmetric slow-wave sleep, one half of the brain is in deep sleep, a form of non-rapid eye movement sleep and the eye corresponding to this half is closed while the other eye remains open. When examined by low-voltage electroencephalography (EEG), the characteristic slow-wave sleep tracings are seen from one side while the other side shows a characteristic tracing of wakefulness. The phenomenon has been observed in a number of terrestrial, aquatic and avian species. 

Unique physiology, including the differential release of the neurotransmitter acetylcholine, has been linked to the phenomenon. USWS offers a number of benefits, including the ability to rest in areas of high predation or during long migratory flights. The behaviour remains an important research topic because USWS is possibly the first animal behaviour which uses different regions of the brain to simultaneously control sleep and wakefulness. The greatest theoretical importance of USWS is its potential role in elucidating the function of sleep by challenging various current notions. Researchers have looked to animals exhibiting USWS to determine if sleep must be essential; otherwise, species exhibiting USWS would have eliminated the behaviour altogether through evolution.

The amount of time spent sleeping during the unihemispheric slow-wave stage is considerably inferior to the bilateral slow-wave sleep. In the past, aquatic animals, such as dolphins and seals, had to regularly surface in order to breathe and regulate body temperature. USWS might have been generated by the need of getting simultaneously these vital activities in addition to sleep.

Despite the reduced sleep quantity, species having USWS do not present limits at a behavioral or healthy level. Cetaceans, such as dolphins, show a preserved health as well as great memory skills. Indeed, cetaceans, seals and birds compensate for the lack of complete sleep thanks to their efficient immune system, brain plasticity, thermoregulation and restoration of brain energy metabolism.

Physiology

Polysomnogram demonstrating slow-wave sleep.
 

High amplitude EEG is highlighted in red.

 

Slow-wave sleep (SWS), also known as Stage 3, is characterized by a lack of movement and difficulty of arousal. Slow-wave sleep occurring in both hemispheres is referred to as bihemispheric slow-wave sleep (BSWS) and is common among most animals. Slow-wave sleep contrasts with rapid eye movement sleep (REM), which can only occur simultaneously in both hemispheres. In most animals, slow-wave sleep is characterized by high amplitude, low frequency EEG readings. This is also known as the desynchronized state of the brain, or deep sleep.

In USWS, only one hemisphere exhibits the deep sleep EEG while the other hemisphere exhibits an EEG typical of wakefulness with a low amplitude and high frequency. There also exist instances in which hemispheres are in transitional stages of sleep, but they have not been the subject of study due to their ambiguous nature. USWS represents the first known behavior in which one part of the brain controls sleep while another part controls wakefulness.

Generally, when the whole amount of sleeping of each hemisphere is summed, both hemispheres get equal amounts of USWS. However, when every single session is taken into account, a large asymmetry of USWS episodes can be observed. This information suggests that at one time the neural circuit is more active in one hemisphere than on the other one and vice versa the following time.

According to Fuller, awakening is characterized by high activity of neural groups that promote awakening: they activate the cortex as well as subcortical structures and simultaneously inhibit neural groups which promotes sleep. Therefore, sleep is defined by the opposite mechanism. It can be assumed, that cetaceans show a similar structure, but the neural groups are stimulated according to the need of each hemisphere. So, neural mechanisms that promote sleep are predominant in the sleeping hemisphere, while the ones that promote awakening are more active in the non-sleeping hemisphere.

Role of acetylcholine

Due to the origin of USWS in the brain, neurotransmitters are believed to be involved in its regulation. The neurotransmitter acetylcholine has been linked to hemispheric activation in northern fur seals. Researchers studied seals in controlled environments by observing behaviour as well as through surgically implanted EEG electrodes. Acetylcholine is released in nearly the same amounts per hemisphere in bilateral slow-wave sleep. However, in USWS, the maximal release of the cortical acetylcholine neurotransmitter is lateralized to the hemisphere exhibiting an EEG trace resembling wakefulness. The hemisphere exhibiting SWS is marked by the minimal release of acetylcholine. This model of acetylcholine release has been further discovered in additional species such as the bottlenose dolphin.

Eye opening

In domestic chicks and other species of birds exhibiting USWS, one eye remained open contra-lateral (on the opposite side) to the "awake" hemisphere. The closed eye was shown to be opposite the hemisphere engaging in slow-wave sleep. Learning tasks, such as those including predator recognition, demonstrated the open eye could be preferential. This has also been shown to be the favored behavior of belugas, although inconsistencies have arisen directly relating the sleeping hemisphere and open eye. Keeping one eye open aids birds in engaging in USWS while mid-flight as well as helping them observe predators in their vicinity.

Given that USWS is preserved also in blind animals or during a lack of visual stimuli, it cannot be considered as a consequence of keeping an eye open while sleeping. Furthermore, the open eye in dolphins does not forcibly activate the contralateral hemisphere. Although unilateral vision plays a considerable role in keeping active the contralateral hemisphere, it is not the motive power of USWS. Consequently, USWS might be generated by endogenous mechanisms.

Thermoregulation

Brain temperature has been shown to drop when a sleeping EEG is exhibited in one or both hemispheres. This decrease in temperature has been linked to a method to thermoregulate and conserve energy while maintaining the vigilance of USWS. The thermoregulation has been demonstrated in dolphins and is believed to be conserved among species exhibiting USWS.

Anatomical variations

Smaller corpus callosum

USWS requires hemispheric separation to isolate the cerebral hemispheres enough to ensure that the one can engage in SWS while the other is awake. The corpus callosum is the anatomical structure in the mammalian brain which allows for interhemispheric communication. Cetaceans have been observed to have a smaller corpus callosum when compared to other mammals. Similarly, birds lack a corpus callosum altogether and have only few, means of interhemispheric connections. Other evidence contradicts this potential role; sagittal transsections of the corpus callosum have been found to result in strictly bihemispheric sleep. As a result, it seems this anatomical difference, though well correlated, does not directly explain the existence of USWS.

Noradrenergic diffuse modulatory system variations

A promising method of identifying the neuroanatomical structures responsible for USWS is continuing comparisons of brains that exhibit USWS with those that do not. Some studies have shown induced asynchronous SWS in non-USWS-exhibiting animals as a result of sagittal transactions of subcortical regions, including the lower brainstem, while leaving the corpus callosum intact. Other comparisons found that mammals exhibiting USWS have a larger posterior commissure and increased decussation of ascending fibres from the locus coeruleus in the brainstem. This is consistent with the fact that one form for neuromodulation, the noradrenergic diffuse modulatory system present in the locus coeruleus, is involved in regulating arousal, attention, and sleep-wake cycles.

During USWS the proportion of noradrenergic secretion is asymmetric. It is indeed high in the awaken hemisphere and low in the sleeping one. The continuous discharge of noradrenergic neurons stimulates heat production: the awake hemisphere of dolphins shows a higher, but stable, temperature. On the contrary, the sleeping hemisphere reports a slightly lower temperature compared to the other hemisphere. According to researchers, the difference in hemispheric temperatures may play a role in shifting between the SWS and awaken status.

Complete crossing of the optic nerve

Complete crossing (decussation) of the nerves at the optic chiasm in birds has also stimulated research. Complete decussation of the optic tract has been seen as a method of ensuring the open eye strictly activates the contralateral hemisphere. Some evidence indicates that this alone is not enough as blindness would theoretically prevent USWS if retinal nerve stimuli were the sole player. However, USWS is still exhibited in blinded birds despite the absence of visual input.

Benefits

Many species of birds and marine mammals have advantages due to their unihemispheric slow-wave sleep capability, including, but not limited to, increased ability to evade potential predators and the ability to sleep during migration. Unihemispheric sleep allows visual vigilance of the environment, preservation of movement, and in cetaceans, control of the respiratory system.

Adaptation to high-risk predation

Most species of birds are able to detect approaching predators during unihemispheric slow-wave sleep. During the flight, birds maintain visual vigilance by utilizing USWS and by keeping one eye open. The utilization of unihemispheric slow-wave sleep by avian species is directly proportional to the risk of predation. In other words, the usage of USWS of certain species of birds increases as the risk of predation increases.

Survival of the fittest adaptation

The evolution of both cetaceans and birds may have involved some mechanisms for the purpose of increasing the likelihood of avoiding predators. Certain species, especially of birds, that acquired the ability to perform unihemispheric slow-wave sleep had an advantage and were more likely to escape their potential predators over other species that lacked the ability.

Regulation based on surroundings

Birds can sleep more efficiently with both hemispheres sleeping simultaneously (bihemispheric slow-wave sleep) when in safe conditions, but will increase the usage of USWS if they are in a potentially more dangerous environment. It is more beneficial to sleep using both hemispheres; however, the positives of unihemispheric slow-wave sleep prevail over its negatives under extreme conditions. While in unihemispheric slow-wave sleep, birds will sleep with one open eye towards the direction from which predators are more likely to approach. When birds do this in a flock, it's called the "group edge effect".

The mallard is one bird that has been used experimentally to illustrate the "group edge effect". Birds positioned at the edge of the flock are most alert, scanning often for predators. These birds are more at risk than the birds in the center of the flock and are required to be on the lookout for both their own safety and the safety of the group as a whole. They have been observed spending more time in unihemispheric slow-wave sleep than the birds in the center. Since USWS allows for the one eye to be open, the cerebral hemisphere that undergoes slow-wave sleep varies depending on the position of the bird relative to the rest of the flock. If the bird's left side is facing outward, the left hemisphere will be in slow-wave sleep; if the bird's right side is facing outward, the right hemisphere will be in slow-wave sleep. This is because the eyes are contra-lateral to the left and right hemispheres of the cerebral cortex. The open eye of the bird is always directed towards the outside of the group, in the direction from which predators could potentially attack.

Surfacing for air and pod cohesion

Unihemispheric slow-wave sleep seems to allow the simultaneous sleeping and surfacing to breathe of aquatic mammals including both dolphins and seals. Bottlenose dolphins are one specific species of cetaceans that have been proven experimentally to use USWS in order to maintain both swimming patterns and the surfacing for air while sleeping.

In addition, a reversed version of the "group edge effect" has been observed in pods of Pacific white-sided dolphins. Dolphins swimming on the left side of the pod has their right eyes open while dolphins swimming on the right side of the pod have their left eyes open. Unlike in some species of birds, the open eyes of these cetaceans are facing the inside of the group, not the outside. The dangers of possible predation do not play a significant role during USWS in Pacific white-sided dolphins. It has been suggested that this species utilizes this reversed version of the "group edge effect" in order to maintain pod formation and cohesion while maintaining unihemispheric slow-wave sleep.

Rest during long bird flights

While migrating, birds may undergo unihemispheric slow-wave sleep in order to simultaneously sleep and visually navigate flight. Certain species may thus avoid a need to make frequent stops along the way. Certain bird species are more likely to utilize USWS during soaring flight, but it is possible for birds to undergo USWS in flapping flight as well. Much is still unknown about the usage of unihemispheric slow-wave sleep, since the inter-hemispheric EEG asymmetry that is viewed in idle birds may not be equivalent to that of birds that are flying.

Species exhibiting USWS

Although humans show reduced left-hemisphere delta waves during slow-wave sleep in an unfamiliar bedchamber, this is not wakeful alertness of USWS, which is impossible in humans.

Aquatic mammals

Cetaceans

Of all the cetacean species, USWS has been found to be exhibited in the following species

• Amazon river dolphin (Inia geoffrensis)
• Beluga whale (Delphinapterus leucus)
• Bottlenose dolphin (Tursiops truncates)
• Pacific white-sided dolphin (Lagenorhynchus obliquidens)
• Pilot whale (Globicephala scammoni)
• Porpoise (Phocoena phocoena)

Pinnipeds

Though pinnipeds are capable of sleeping on either land or water, it has been found that pinnipeds that exhibit USWS do so at a higher rate while sleeping in water. Though no USWS has been observed in true seals, four different species of eared seals have been found to exhibit USWS including

• Northern fur seal (Callorhinus ursinus)

Significant research has been done illustrating that the northern fur seal can alternate between BSWS and USWS depending on its location while sleeping. While on land, 69% of all SWS is present bilaterally; however, when sleep takes place in water, 68% of all SWS is found with interhemispheric EEG asymmetry, indicating USWS.

• Southern sea lion (Otari bryonia)
• Steller sea lion (Eumetopias jubatus)

Sirenia

In the final order of aquatic mammals, sirenia, experiments have only exhibited USWS in the Amazonian manatee (Trichechus inunguis).

Birds

Common swift

The common swift (Apus apus) was the best candidate for research aimed at determining whether or not birds exhibiting USWS can sleep in flight. The selection of the common swift as a model stemmed from observations elucidating the fact that the common swift left its nest at night, only returning in the early morning. Still, evidence for USWS is strictly circumstantial and based on the notion that if swifts must sleep to survive, they must do so via aerial roosting as little time is spent sleeping in a nest.

Multiple other species of birds have also been found to exhibit USWS including

• Common blackbird (Turdus merula)
• Domestic chicken (Gallus gallus domesticus),
• Glaucous-winged gull (Larus glaucescens)
• Japanese quail (Coturnix japonica)
• Mallard (Anas platyrhynchos).
• Northern bobwhite (Colinus virginianus),
• Orange-fronted parakeet (Aratinga canicularis)
• Peregrine falcon (Falco peregrinus)
• White-crowned sparrow (Zonotrichia leucophrys gambelii)

Future research

Recent studies have illustrated that the white-crowned sparrow, as well as other passerines, have the capability of sleeping most significantly during the migratory season while in flight. However, the sleep patterns in this study were observed during migratory restlessness in captivity and might not be analogous to those of free-flying birds. Free-flying birds might be able to spend some time sleeping while in non-migratory flight as well when in the unobstructed sky as opposed to in controlled captive conditions. To truly determine if birds can sleep in flight, recordings of brain activity must take place during flight instead of after landing. A method of recording brain activity in pigeons during flight has recently proven promising in that it could obtain an EEG of each hemisphere but for relatively short periods of time. Coupled with simulated wind tunnels in a controlled setting, these new methods of measuring brain activity could elucidate the truth behind whether or not birds sleep during flight.

Additionally, based on research elucidating the role of acetylcholine in control of USWS, additional neurotransmitters are being researched to understand their roles in the asymmetric sleep model.

Schizoaffective disorder

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Schizoaffective_disorder

Schizoaffective disorder
Specialty	Psychiatry
Symptoms	Hallucinations, delusions, disorganized thinking, depressed mood, manic behavior
Complications	Social isolation, suicide
Types	Bipolar type, depressive type
Causes	Unknown
Risk factors	Genetics, brain chemistry and structure, stress, drug use, trauma from abuse
Medication	Antipsychotics, mood stabilizers

Schizoaffective disorder (SZA, SZD or SAD) is a mental disorder characterized by abnormal thought processes and an unstable mood. The diagnosis is made when the person has symptoms of both schizophrenia (usually psychosis) and a mood disorder—either bipolar disorder or depression—but does not meet the diagnostic criteria for schizophrenia or a mood disorder individually. The main criterion for the schizoaffective disorder diagnosis is the presence of psychotic symptoms for at least two weeks without any mood symptoms present. Schizoaffective disorder can often be misdiagnosed when the correct diagnosis may be psychotic depression, psychotic bipolar disorder, schizophreniform disorder, or schizophrenia. It is imperative for providers to accurately diagnose patients, as treatment and prognosis differs greatly for each of these diagnoses.

There are two types of schizoaffective disorder: the bipolar type, which is distinguished by symptoms of mania, hypomania, or mixed episode; and the depressive type, which is distinguished by symptoms of depression only. Common symptoms of the disorder include hallucinations, delusions, and disorganized speech and thinking. Auditory hallucinations, or "hearing voices," are most common. The onset of symptoms usually begins in young adulthood.

Genetics (researched in the field of genomics); problems with neural circuits; chronic early, and chronic or short-term current environmental stress appear to be important causal factors. No single isolated organic cause has been found, but extensive evidence exists for abnormalities in the metabolism of tetrahydrobiopterin (BH4), dopamine, and glutamic acid in people with schizophrenia, psychotic mood disorders, and schizoaffective disorder. People with schizoaffective disorder are likely to have co-occurring conditions, including anxiety disorders and substance use disorders.

The mainstay of current treatment is antipsychotic medication combined with mood stabilizer medication or antidepressant medication, or both. There is growing concern by some researchers that antidepressants may increase psychosis, mania, and long-term mood episode cycling in the disorder. When there is risk to self or others, usually early in treatment, hospitalization may be necessary. Psychiatric rehabilitation, psychotherapy, and vocational rehabilitation are very important for recovery of higher psychosocial function. As a group, people with schizoaffective disorder that were diagnosed using DSM-IV and ICD-10 criteria (which have since been updated) have a better outcome, but have variable individual psychosocial functional outcomes compared to people with mood disorders, from worse to the same. Outcomes for people with DSM-5 diagnosed schizoaffective disorder depend on data from prospective cohort studies, which have not been completed yet. The DSM-5 diagnosis was updated because DSM-IV criteria resulted in overuse of the diagnosis; that is, DSM-IV criteria led to many patients being misdiagnosed with the disorder. DSM-IV prevalence estimates were less than one percent of the population, in the range of 0.5–0.8 percent; newer DSM-5 prevalence estimates are not yet available.

Signs and symptoms

Schizoaffective disorder is defined by mood disorder-free psychosis in the context of a long-term psychotic and mood disorder. Psychosis must meet criterion A for schizophrenia which may include delusions, hallucinations, disorganized speech, thinking or behavior and negative symptoms. Both delusions and hallucinations are classic symptoms of psychosis. Delusions are false beliefs which are strongly held despite evidence to the contrary. Beliefs should not be considered delusional if they are in keeping with cultural beliefs. Delusional beliefs may or may not reflect mood symptoms (for example, someone experiencing depression may or may not experience delusions of guilt). Hallucinations are disturbances in perception involving any of the five senses, although auditory hallucinations (or "hearing voices") are the most common. A lack of responsiveness or negative symptoms include alogia (lack of spontaneous speech), blunted affect (reduced intensity of outward emotional expression), avolition (loss of motivation), and anhedonia (inability to experience pleasure). Negative symptoms can be more lasting and more debilitating than positive symptoms of psychosis.

Mood symptoms are of mania, hypomania, mixed episode, or depression, and tend to be episodic rather than continuous. A mixed episode represents a combination of symptoms of mania and depression at the same time. Symptoms of mania include elevated or irritable mood, grandiosity (inflated self-esteem), agitation, risk-taking behavior, decreased need for sleep, poor concentration, rapid speech, and racing thoughts. Symptoms of depression include low mood, apathy, changes in appetite or weight, disturbances in sleep, changes in motor activity, fatigue, guilt or feelings of worthlessness, and suicidal thinking.

DSM-5 states that if a patient only experiences psychotic symptoms during a mood episode, their diagnosis is Mood Disorder with Psychotic Features and not Schizophrenia or Schizoaffective Disorder. If the patient experiences psychotic symptoms without mood symptoms for longer than a two-week period, their diagnosis is either Schizophrenia or Schizoaffective Disorder. If mood disorder episodes are present for the majority and residual course of the illness and up until the diagnosis, the patient can be diagnosed with Schizoaffective Disorder.

Causes

A combination of genetic and environmental factors are believed to play a role in the development of schizoaffective disorder.

Genetic studies do not support the view that schizophrenia, psychotic mood disorders and schizoaffective disorder are distinct etiological entities, but rather the evidence suggests the existence of common inherited vulnerability that increases the risks for all these syndromes. Some susceptibility pathways may be specific for schizophrenia, others for bipolar disorder, and yet other mechanisms and genes may confer risk for mixed schizophrenic and affective [or mood disorder] psychoses, but there is no support from genetics for the view that these are distinct disorders with distinct etiologies and pathogenesis. Laboratory studies of putative endophenotypes, brain imaging studies, and post mortem studies shed little additional light on the validity of the schizoaffective disorder diagnosis, as most studies combine subjects with different chronic psychoses in comparison to healthy subjects.

— According to William T. Carpenter the head of the University of Maryland, Baltimore School of Medicine DSM-5 psychotic disorders workgroup, and others. 

Viewed broadly then, biological and environmental factors interact with a person's genes in ways which may increase or decrease the risk for developing schizoaffective disorder; exactly how this happens (the biological mechanism) is not yet known. Schizophrenia spectrum disorders, of which schizoaffective disorder is a part, have been increasingly linked to advanced paternal age at the time of conception, a known cause of genetic mutations. The physiology of people diagnosed with schizoaffective disorder appears to be similar, but not identical, to that of those diagnosed with schizophrenia and bipolar disorder; however, human neurophysiological function in normal brain and mental disorder syndromes is not fully understood.

Substance abuse

A clear causal connection between drug use and psychotic spectrum disorders, including schizoaffective disorder, has been difficult to prove. In the specific case of cannabis (marijuana), however, evidence supports a link between earlier onset of psychotic illness and cannabis use. The more often cannabis is used, particularly in early adolescence, the more likely a person is to develop a psychotic illness, with frequent use being correlated with double the risk of psychosis and schizoaffective disorder. A 2009 Yale review stated that in individuals with an established psychotic disorder, cannabinoids can exacerbate symptoms, trigger relapse, and have negative consequences on the course of the illness. While cannabis use is accepted as a contributory cause of schizoaffective disorder by many, it remains controversial, since not all young people who use cannabis later develop psychosis, but those who do use cannabis have an increased odds ratio of about 3. Certain drugs can imitate symptoms of schizophrenia (which we know has similar symptoms to schizoaffective disorder). This is important to note when including that substance-induced psychosis should be ruled out when diagnosing patients so that patients are not misdiagnosed.

Diagnosis

Psychosis as a symptom of a psychiatric disorder is first and foremost a diagnosis of exclusion. So a new-onset episode of psychosis cannot be considered to be a symptom of a psychiatric disorder until other relevant and known medical causes of psychosis are excluded, or ruled out. Many clinicians improperly perform, or entirely miss this step, introducing avoidable diagnostic error and misdiagnosis.

An initial assessment includes a comprehensive history and physical examination. Although no biological laboratory tests exist which confirm schizoaffective disorder, biological tests should be performed to exclude psychosis associated with or caused by substance use, medications, toxins or poisons, surgical complications, or other medical illnesses. Since non-medical mental health practitioners are not trained to exclude medical causes of psychosis, people experiencing psychosis should be referred to an emergency department or hospital.

Delirium should be ruled out, which can be distinguished by visual hallucinations, acute onset and fluctuating level of consciousness, indicating other underlying factors which includes medical illnesses. Excluding medical illnesses associated with psychosis is performed by using blood tests to measure:

• Thyroid-stimulating hormone to exclude hypo- or hyperthyroidism,
• Basic electrolytes and serum calcium to rule out a metabolic disturbance,
• Full blood count including ESR to rule out a systemic infection or chronic disease, and
• Serology to exclude syphilis or HIV infection.

Other investigations which may be performed include:

• EEG to exclude epilepsy, and an
• MRI or CT scan of the head to exclude brain lesions.

Blood tests are not usually repeated for relapse in people with an established diagnosis of schizoaffective disorder, unless there is a specific medical indication. These may include serum BSL if olanzapine has previously been prescribed, thyroid function if lithium has previously been taken to rule out hypothyroidism, liver function tests if chlorpromazine has been prescribed, CPK levels to exclude neuroleptic malignant syndrome, and a urinalysis and serum toxicology screening if substance use is suspected. Assessment and treatment may be done on an outpatient basis; admission to an inpatient facility is considered if there is a risk to self or others.

Because psychosis may be precipitated or exacerbated by common classes of psychiatric medications, such as antidepressants, ADHD stimulant medications, and sleep medications, prescribed medication-induced psychosis should be ruled out, particularly for first-episode psychosis. This is an essential step to reduce diagnostic error and to evaluate potential medication sources of further patient harm. Regarding prescribed medication sources of patient harm, Yale School of Medicine Professor of Psychiatry Malcolm B. Bowers, Jr, MD wrote:

Illicit drugs aren't the only ones that precipitate psychosis or mania—prescribed drugs can too, and in particular, some psychiatric drugs. We investigated this and found that about 1 in 12 psychotic or manic patients in an inpatient psychiatric facility are there due to antidepressant-induced psychosis or mania. That's unfortunate for the field [of psychiatry] and disastrous for some of our patients.

It is important to be understood here. I want to call attention to the fact that some persons with a family history of even the subtler forms of bipolar disorder or psychosis are more vulnerable than others to the mania- or psychosis-inducing potential of antidepressants, stimulants and sleeping medications. While I'm not making a blanket statement against these medications, I am urging caution in their use. I believe [clinicians] should ask patients and their families whether there is a family history of bipolar disorder or psychosis before prescribing these medications. Most patients and their families don't know the answer when they are first asked, so time should be allowed for the patient to ask family or relatives, between the session when asked by [the clinician] and a follow-up session. This may increase the wait for a medication slightly, but because some patients are vulnerable, this is a necessary step for [the clinician] to take. I believe that psychiatry as a field has not emphasized this point sufficiently. As a result, some patients have been harmed by the very treatments that were supposed to help them; or to the disgrace of psychiatry, harmed and then misdiagnosed.

Substance-induced psychosis should also be ruled out. Both substance- and medication-induced psychosis can be excluded to a high level of certainty while the person is psychotic, typically in an emergency department, using both a

• Broad spectrum urine toxicology screening, and a
• Full serum toxicology screening (of the blood).

Some dietary supplements may also induce psychosis or mania, but cannot be ruled out with laboratory tests. So a psychotic person's family, partner, or friends should be asked whether he or she is currently taking any dietary supplements.

Common mistakes made when diagnosing psychotic patients include:

• Not properly excluding delirium,
• Missing a toxic psychosis by not screening for substances and medications,
• Not appreciating medical abnormalities (e.g., vital signs),
• Not obtaining a medical history and family history,
• Indiscriminate screening without an organizing framework,
• Not asking family or others about dietary supplements,
• Premature diagnostic closure, and
• Not revisiting or questioning the initial diagnostic impression of primary psychiatric disorder.

Only after these relevant and known causes of psychosis have been ruled out can a psychiatric differential diagnosis be made. A mental health clinician will incorporate family history, observation of a psychotic person's behavior while the person is experiencing active symptoms, to begin a psychiatric differential diagnosis. Diagnosis also includes self-reported experiences, as well as behavioral abnormalities reported by family members, friends, or significant others. Mistakes in this stage include:

• Not screening for dissociative disorders. Dissociative identity disorder and psychotic symptoms in schizoaffective disorder have considerable overlap, yet a different overall treatment approach.

DSM-5 criteria

The most widely used criteria for diagnosing schizoaffective disorder are from the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders-5.

The DSM-IV schizoaffective disorder definition was plagued by problems of being inconsistently (or unreliably) used on patients; when the diagnosis is made, it doesn't stay with most patients over time; and it has questionable diagnostic validity (that is, it doesn't describe a distinct disorder, nor predict any particular outcome). These problems have been slightly reduced (or "modestly improved") in the DSM-5 according to Carpenter.

When psychotic symptoms are confined to an episode of mania or depression (with or without mixed features), the diagnosis is that of a “psychotic” mood disorder, namely either psychotic bipolar disorder or psychotic major depression. Only when psychotic states persist in a sustained fashion for two weeks or longer without concurrent affective symptoms is the diagnosis schizoaffective disorder, schizophreniform disorder or schizophrenia.

The second cardinal guideline in the DSM-5 diagnosis of schizoaffective disorder is one of timeframe.

DSM-5 requires two episodes of psychosis (whereas DSM-IV needed only one) to qualify for the schizoaffective disorder diagnosis. As such, it is no longer an "episode diagnosis." The new schizoaffective framework looks at the time from "the [first episode of] psychosis up to the current episode [of psychosis], rather than only defining a single episode with [co-occurring] psychotic and mood syndromes." Specifically, one of the episodes of psychosis must last a minimum of two weeks without mood disorder symptoms, but the person may be mildly to moderately depressed while psychotic. The other period of psychosis "requires the overlap of mood [disorder] symptoms with psychotic symptoms to be conspicuous" and last for a greater portion of the disorder.

These two changes are intended by the DSM-5 workgroup to accomplish two goals:

• Increase the diagnosis' consistency (or reliability) when it is used;
• Significantly decrease the overall use of the schizoaffective disorder diagnosis.

If the schizoaffective diagnosis is used less often, other diagnoses (like psychotic mood disorders and schizophrenia) are likely to be used more often; but this is hypothetical until real-world data arrive. Validity problems with the diagnosis remain and await further work in the fields of psychiatric genetics, neuroimaging, and cognitive science that includes the overlapping fields of cognitive, affective, and social neuroscience, which may change the way schizoaffective disorder is conceptualized and defined in future versions of the DSM and ICD.

Types

One of two types of schizoaffective disorder may be noted in a diagnosis based on the mood component of the disorder:

• Bipolar type, when the disturbance includes manic episodes, hypomania, or mixed episodes—major depressive episodes also typically occur;
• Depressive type, when the disturbance includes major depressive episodes exclusively—that is, without manic, hypomanic, or mixed episodes.

Problems with DSM-IV schizoaffective disorder

The American Psychiatric Association's DSM-IV criteria for schizoaffective disorder persisted for 19 years (1994–2013). Clinicians adequately trained in diagnosis used the schizoaffective diagnosis too often, largely because the criteria were poorly defined, ambiguous, and hard to use (or poorly operationalized). Poorly trained clinicians used the diagnosis without making necessary exclusions of common causes of psychosis, including some prescribed psychiatric medications. Specialty books written by experts on schizoaffective disorder have existed for over eight years before DSM-5 describing the overuse of the diagnosis.

Carpenter and the DSM-5 schizoaffective disorders workgroup analyzed data made available to them in 2009, and reported in May 2013 that:

a recent review of psychotic disorders from large private insurance and Medicare databases in the U.S. found that the diagnosis of DSM-IV schizoaffective disorder was used for about a third of cases with non-affective psychotic disorders. Hence, this unreliable and poorly defined diagnosis is clearly overused.

As stated above, the DSM-IV schizoaffective disorder diagnosis is very inconsistently used or unreliable. A diagnosis is unreliable when several different mental health professionals observing the same individual make different diagnoses excessively. Even when a structured DSM-IV diagnostic interview and best estimate procedures were made by experts in the field that included information from family informants and prior clinical records, reliability was still poor for the DSM-IV schizoaffective diagnosis.

The DSM-IV schizoaffective diagnosis isn't stable over time either. An initial diagnosis of schizoaffective disorder during time spent at a psychiatric inpatient facility was stable at 6-month and 24-month follow ups for only 36% of patients. By comparison, diagnostic stability was 92% for schizophrenia, 83% for bipolar disorder and 74% for major depression. Most patients diagnosed with DSM-IV schizoaffective disorder are later diagnosed with a different disorder, and that disorder is more stable over time than the DSM-IV schizoaffective disorder diagnosis.

In April 2009, Carpenter and the DSM-5 schizoaffective disorder workgroup reported that they were "developing new criteria for schizoaffective disorder to improve reliability and face validity," and were "determining whether the dimensional assessment of mood [would] justify a recommendation to drop schizoaffective disorder as a diagnostic category." Speaking to an audience at the May 2009 annual conference of the American Psychiatric Association, Carpenter said:

We had hoped to get rid of schizoaffective [disorder] as a diagnostic category [in the DSM-5] because we don't think it's [a] valid [scientific entity] and we don't think it's reliable. On the other hand, we think it's absolutely indispensable to clinical practice.

A major reason why DSM-IV schizoaffective disorder was indispensable to clinical practice is because it offered clinicians a diagnosis for patients with psychosis in the context of mood disorder whose clinical picture, at the time diagnosed, appeared different from DSM-IV "schizophrenia" or "mood disorder with psychotic features."

But DSM-IV schizoaffective disorder carries an unnecessarily worse prognosis than a "mood disorder with psychotic features" diagnosis, because long-term data revealed that a significant proportion of DSM-IV schizoaffective disorder patients had 15-year outcomes indistinguishable from patients with mood disorders with or without psychotic features, even though the clinical picture at the time of first diagnosis looked different from both schizophrenia and mood disorders.

These problems with the DSM-IV schizoaffective disorder definition result in most people the diagnosis is used on being misdiagnosed; furthermore, outcome studies done 10 years after the diagnosis was released showed that the group of patients defined by the DSM-IV and ICD-10 schizoaffective diagnosis had significantly better outcomes than predicted, so the diagnosis carries a misleading and unnecessarily poor prognosis. The DSM-IV criteria for schizoaffective disorder will continue to be used on U.S. board examinations in psychiatry through the end of 2014; established practitioners may continue to use the problematic DSM-IV definition much further into the future also. 

DSM-5 research directions

The new schizoaffective disorder criteria continue to have questionable diagnostic validity. Questionable diagnostic validity does not doubt that people with symptoms of psychosis and mood disorder need treatment—psychosis and mood disorder must be treated. Instead, questionable diagnostic validity means there are unresolved problems with the way the DSM-5 categorizes and defines schizoaffective disorder.

Emil Kraepelin's dichotomy (c. 1898) continues to influence classification and diagnosis in psychiatry

A core concept in modern psychiatry since DSM-III was released in 1980, is the categorical separation of mood disorders from schizophrenia, known as the Kraepelinian dichotomy. Emil Kraepelin introduced the idea that schizophrenia was separate from mood disorders after observing patients with symptoms of psychosis and mood disorder, over a century ago, in 1898. This was a time before genetics were known and before any treatments existed for mental illness. The Kraepelinian dichotomy wasn't used for DSM-I and DSM-II because both manuals were influenced by the dominant psychodynamic psychiatry of the time, but the designers of DSM-III wanted to use more scientific and biological definitions. Consequently, they looked to psychiatry's history and decided to use the Kraepelinian dichotomy as a foundation for the classification system.

The Kraepelinian dichotomy continues to be used in DSM-5 despite having been challenged by data from modern psychiatric genetics for over eight years, and there is now evidence of a significant overlap in the genetics of schizophrenia and bipolar disorder. According to this genetic evidence, the Kraepelinian categorical separation of mood disorders from schizophrenia at the foundation of the current classification and diagnostic system is a mistaken false dichotomy.

The dichotomy at the foundation of the current system forms the basis for a convoluted schizoaffective disorder definition in DSM-IV that resulted in excessive misdiagnosis. Real life schizoaffective disorder patients have significant and enduring symptoms that bridge what are incorrectly assumed to be categorically separate disorders, schizophrenia and bipolar disorder. People with psychotic depression, bipolar disorder with a history of psychosis, and schizophrenia with mood symptoms also have symptoms that bridge psychosis and mood disorders. The categorical diagnostic manuals don't reflect reality in their separation of psychosis (via the schizophrenia diagnosis) from mood disorder, nor do they currently emphasize the actual overlap found in real-life patients. Thus, they are likely to continue to introduce either-or conceptual and diagnostic error, by way of confirmation bias into clinicians' mindsets, hindering accurate assessment and treatment.

The new definition continues the lack of parsimony of the old definition. Simpler, clearer, and more usable definitions of the diagnosis were supported by certain members of the DSM-5 workgroup (see next paragraph); these were debated but deemed premature, because more "research [is] needed to establish a new classification system of equal or greater validity" to the existing system. Because of DSM-5's continuing problematic categorical foundation, schizoaffective disorder's conceptual and diagnostic validity remains doubtful. After enough research is completed and data exists, future diagnostic advances will need to either eliminate and replace, or soften and bridge, the hard categorical separation of mood disorders from schizophrenia; most likely using a spectrum or dimensional approach to diagnosis.

More parsimonious definitions than the current one were considered by Carpenter and the DSM-5 workgroup:

One option for the DSM-5 would have been to remove the schizoaffective disorder category and to add affective [or mood] symptoms [that is, mania, hypomania, mixed episode, or depression] as a dimension to schizophrenia and schizophreniform disorder or to define a single category for the co-occurrence of psychosis and mood symptoms. This option was extensively debated but ultimately deemed to be premature in the absence of sufficient clinical and theoretical validating data justifying such a … reconceptualization. Additionally, there appeared to be no practical way to introduce affect [or mood] dimensions covering the entire course of illness, that would capture the current concept of periods of psychosis related and unrelated to mood episodes.

[N]o valid biomarkers or laboratory measures have emerged to distinguish between affective psychosis [or psychotic mood disorders] and schizophrenia. To the contrary, the idea of a dichotomy between these types of conditions has proven naïve. [T]he admixture of “schizophrenic” and affective [or mood] symptoms is a feature of many, or even most, cases with severe mental illness. Most presenting symptoms of psychosis have little validity in determining diagnosis, prognosis, or treatment response in psychosis. [U]ltimately a more … dimensional approach [to assessment and treatment] will be required.

The field of psychiatry has begun to question its assumptions and analyze its data in order to merge closer with evidence-based medicine. The removal of the "episode diagnosis," and the addition of two episodes of psychosis, as qualifications for the DSM-5 schizoaffective diagnosis, may improve the diagnosis' consistency over DSM-IV for research purposes, where diagnostic criteria are by necessity followed exactingly. But the new definition remains long, unwieldy, and perhaps still not very useful for community clinicians—with two psychoses, one for two weeks minimum and without mood disorder (but the person can be mildly or moderately depressed) and the other with significant mood disorder and psychosis lasting for most of the time, and with lasting mood symptoms for most of the residual portion of the illness. Community clinicians used the previous definition "for about a third of cases with non-affective psychotic disorders." Non-affective psychotic disorders are, by definition, not schizoaffective disorder. For clinicians to make such sizeable errors of misdiagnosis may imply systemic problems with the schizoaffective disorder diagnosis itself. Already, at least one expert believes the new schizoaffective definition hasn't gone far enough to solve the previous definition's problems.

From a scientific standpoint, modern clinical psychiatry is still a very young, underdeveloped medical specialty because its target organ, the human brain, is not yet well understood. The human brain's neural circuits, for example, are just beginning to be mapped by modern neuroscience in the Human Connectome Project and CLARITY. Clinical psychiatry, furthermore, has begun to understand and acknowledge its current limitations—but further steps by the field are required to significantly reduce misdiagnosis and patient harm; this is crucial both for responsible patient care and to retain public trust. Looking forward, a paradigm shift is needed in psychiatric research to address unanswered questions about schizoaffective disorder. The dimensional Research Domain Criteria project currently being developed by the U.S. National Institutes of Mental Health, may be the specific problem solving framework psychiatry needs to develop a more scientifically mature understanding of schizoaffective disorder as well as all other mental disorders.

Treatment

The primary treatment of schizoaffective disorder is medication, with improved outcomes using combined long-term psychological and social supports. Hospitalization may occur for severe episodes either voluntarily or (if mental health legislation allows it) involuntarily. Long-term hospitalization is uncommon since deinstitutionalization beginning in the 1950s, although it still occurs. Community support services including drop-in centers, visits by members of a community mental health team, supported employment and support groups are common. Evidence indicates that regular exercise has a positive effect on the physical and mental health of those with schizoaffective disorder.

Participating in internet forums is sometimes used by people with schizoaffective disorder in addition to outpatient medication treatment.

Therapy

Skillfully delivered psychosocial treatments are perhaps the most important component of pushing for and encouraging improved overall functioning in schizoaffective disorder. Supportive psychotherapy and cognitive behavioral therapy are both helpful. Intensive case management (ICM) has been shown to reduce hospitalizations, improve adherence to treatment, and improve social functioning. With ICM, clients are assigned a case manager responsible for coordination of care and assisting clients to access supports to address needs in multiple areas related to well-being, including housing. 

High quality psychosocial or psychiatric rehabilitation is very important for recovery from schizoaffective disorder. Psychiatric or psychosocial rehabilitation focuses on solving community integration problems such as obtaining and keeping housing and increasing involvement in positive social groups. It also focuses on improving and increasing activities of daily living; increasing daily healthy habits (such as normalizing sleep-wake cycles; increasing early morning natural light exposure; increasing moderate exercise [such as 20–30 minutes of moderate to brisk early morning to pre-afternoon walking daily, in order to help normalize circadian rhythms]; helping individuals understand the specific benefits of healthy food choices; increasing stress-reduction activities such as yoga, tai chi, or meditation); and decreasing unhealthy behaviors (such as substance abuse and smoking); thereby significantly improving quality of life. High quality psychiatric rehabilitation may also focus on vocational rehabilitation including preparing the client for volunteer, part-time paid work, returning to school for further education, job skills training for full-time flexible or supported employment, and other client self-improvement efforts. Core principles of effective psychiatric rehabilitation must include providing hope when the client lacks it, respect for the client wherever they are in the recovery process, empowering the client, teaching the client wellness planning, and emphasizing the importance for the client to develop social support networks. A long-term goal of psychiatric and vocational rehabilitation is that the client learn and actively engage in active stress management while in education or employment, while receiving treatment. 

Psychiatric rehabilitation consists of eight main areas:

• Psychiatric (symptom reduction and management)
• Health and Medical (maintaining consistency of care)
• Housing (safe environments)
• Basic living skills (hygiene, meals [including increasing healthy food intake and reducing processed food intake], safety, planning and chores)
• Social (relationships, family boundaries, communication and integration of client into the community)
• Education and vocation (coping skills, motivation and suitable goals chosen by client)
• Finance (personal budget)
• Community and legal (resources)

Medication

Antipsychotic medication is usually required both for acute treatment and the prevention of relapse. There is no single antipsychotic of choice in treating schizoaffective disorder, but atypical antipsychotics should be considered because they have mood-stabilizing activity. Paliperidone is an antipsychotic with FDA approval for the treatment of schizoaffective disorder. Antipsychotics should be used at the minimum dose necessary to control symptoms. Potential side effects include extrapyramidal symptoms, including tremor, muscle stiffness, and restlessness or akathisia. Atypical antipsychotics carry a risk of metabolic syndrome, including weight gain, increased blood sugar, and increased blood cholesterol, so regular monitoring of weight and blood work should be carried out. Some atypical antipsychotics, such as ziprasidone and aripiprazole, are associated with less risk than others, such as olanzapine. Medication choice is based on how effectively it reduces symptoms, how few side effects it causes, and cost. 

In people with treatment-refractory psychosis, a clozapine trial should be considered. Clozapine is an atypical antipsychotic that is recognized as being particularly effective when other antipsychotic agents have failed. Clozapine should also be considered in people with chronic and persistent suicidal thinking and behaviour, as it has been shown to reduce the risk of suicide in patients with schizoaffective disorder and a history of suicidality. Between 0.5 and 2% of patients taking clozapine may develop a life-threatening complication called agranulocytosis, which is a significant drop in a type of white blood cell. Because of this risk, people taking clozapine must have regular monitoring of blood cell counts.

The management of the bipolar type of schizoaffective disorder is similar to the treatment of bipolar disorder, with the goal of preventing mood episodes and cycling. Lithium or anticonvulsant mood stabilizers such as valproic acid, carbamazepine, and lamotrigine are prescribed in combination with an antipsychotic.

For depression, if an antidepressant is prescribed, extra attentiveness must be given by the prescribing clinician due its risk for long-term mood cycle acceleration (that is, inducing more frequent episodes of depression per unit of time) and medication-induced psychosis or mania. For individuals who show emerging psychosis, mania, mixed episode symptoms, or mood cycle acceleration, switching to an antipsychotic plus lithium or lamotrigine is preferable to antidepressants.

For individuals who experience anxiety, anti-anxiety medications can be used, usually on a short-term basis. Benzodiazepines, including lorazepam, clonazepam and diazepam, are types of anti-anxiety medications. Care must be taken when prescribing benzodiazepines due to the risk of the person developing tolerance and dependence.

Electroconvulsive therapy

Electroconvulsive therapy, or ECT, may be considered for patients with schizoaffective disorder experiencing severe depression or severe psychotic symptoms that have not responded to treatment with antipsychotics.

Epidemiology

Schizoaffective disorder is estimated to occur in 0.5 to 0.8 percent of people at some point in their life. 30% of cases occur between the ages of 25 and 35. It is more common in women than men; however, this is because of the high concentration of women in the depressive subcategory, whereas the bipolar subtype has a more or less even gender distribution.

History

The term schizoaffective psychosis was introduced by the American psychiatrist Jacob Kasanin in 1933^[65] to describe an episodic psychotic illness with predominant affective symptoms, that was thought at the time to be a good-prognosis schizophrenia. Kasanin's concept of the illness was influenced by the psychoanalytic teachings of Adolf Meyer and Kasanin postulated that schizoaffective psychosis was caused by "emotional conflicts" of a "mainly sexual nature" and that psychoanalysis "would help prevent the recurrence of such attacks." He based his description on a case study of nine individuals.

Karl Kahlbaum (1828–1899)

Other psychiatrists, before and after Kasanin, have made scientific observations of schizoaffective disorder based on assumptions of a biological and genetic cause of the illness. In 1863, German psychiatrist Karl Kahlbaum (1828–1899) described schizoaffective disorders as a separate group in his vesania typica circularis. Kahlbaum distinguished between cross-sectional and longitudinal observations. (Cross-sectional refers to observation of a single, specific episode of the illness, for example, one episode of psychotic depression; while longitudinal refers to long-term observation of many distinct episodes [similar or different] often occurring over the span of years.) In 1920, psychiatrist Emil Kraepelin (1856–1926), the founder of contemporary scientific psychiatry, observed a "great number" of cases that had characteristics of both groups of psychoses that he originally posited were two distinct and separate illnesses, dementia praecox (now called schizophrenia) and manic depressive insanity (now called bipolar disorders [plural since there are more than one type of bipolar disorder] and recurrent depression).

Kraepelin acknowledged that "there are many overlaps in this area," that is, the area between schizophrenia and mood disorders. In 1959, psychiatrist Kurt Schneider (1887–1967) began to further refine conceptualizations of the different forms that schizoaffective disorders can take since he observed "concurrent and sequential types". (The concurrent type of illness he referred to is a longitudinal course of illness with episodes of mood disorder and psychosis occurring predominantly at the same time [now called psychotic mood disorders or affective psychosis]; while his sequential type refers to a longitudinal course predominantly marked by alternating mood and psychotic episodes.) Schneider described schizoaffective disorders as "cases in-between" the traditional Kraepelinian dichotomy of schizophrenia and mood disorders.

The historical clinical observation that schizoaffective disorder is an overlap of schizophrenia and mood disorders is explained by genes for both illnesses being present in individuals with schizoaffective disorder; specifically, recent research shows that schizophrenia and mood disorders share common genes and polygenic variations.

Emil Kraepelin (1856–1926) Embracing the Kraepelinian dichotomy in DSM-III in 1980, while a step forward from psychodynamic explanations of the disorder, introduced significant problems in schizoaffective disorder diagnosis, as explained recently by the DSM-5 workgroup

 

Schizoaffective disorder was included as a subtype of schizophrenia in DSM-I and DSM-II, though research showed a schizophrenic cluster of symptoms in individuals with a family history of mood disorders whose illness course, other symptoms and treatment outcome were otherwise more akin to bipolar disorder than to schizophrenia. DSM-III placed schizoaffective disorder in "Psychotic Disorders Not Otherwise Specified" before being formally recognized in DSM-III-R. DSM-III-R included its own diagnostic criteria as well as the subtypes, bipolar and depressive. In DSM-IV, published in 1994, schizoaffective disorders belonged to the category "Other Psychotic Disorders" and included almost the same criteria and the same subtypes of illness as DSM-III-R, with the addition of mixed bipolar symptomatology.

DSM-IV and DSM-IV-TR (published in 2000) criteria for schizoaffective disorder were poorly defined and poorly operationalized. These ambiguous and unreliable criteria lasted 19 years and led clinicians to significantly overuse the schizoaffective disorder diagnosis. Patients commonly diagnosed with DSM-IV schizoaffective disorder showed a clinical picture at time of diagnosis that appeared different from schizophrenia or psychotic mood disorders using DSM-IV criteria, but who as a group, were longitudinally determined to have outcomes indistinguishable from those with mood disorders with or without psychotic features. A poor prognosis was assumed to apply to these patients by most clinicians, and this poor prognosis was harmful to many patients. The poor prognosis for DSM-IV schizoaffective disorder was not based on patient outcomes research, but was caused by poorly defined criteria interacting with clinical tradition and belief; clinician enculturation with unscientific assumptions from the diagnosis' history (discussed above), including the invalid Kraepelinian dichotomy; and by clinicians being unfamiliar with the scientific limitations of the diagnostic and classification system.

The DSM-5 schizoaffective disorder workgroup analyzed all of the available research evidence on schizoaffective disorder, and concluded that "presenting symptoms of psychosis have little validity in determining diagnosis, prognosis, or treatment response." Given our understanding of overlapping genetics in bipolar disorders, schizoaffective disorder, and schizophrenia, as well as the overlap in treatments for these disorders; but given the lack of specificity of presenting symptoms for determining diagnosis, prognosis or treatment response in these psychotic illness syndromes, the limits of our knowledge are clearer: Presenting symptoms of psychosis describe only presenting symptoms to be treated, and not much more. Schizoaffective disorder was changed to a longitudinal or life course diagnosis in DSM-5 for this reason.

Research

Evidence is lacking about schizoaffective disorder's (likely multiple) causes and mechanisms (knowing these leads to specific and consistently effective treatments), and about how exactly mood episodes and psychosis are related (knowing this may lead to a simpler, clearer, and more usable behavioral definition of the disorder; as well as a better diagnostic system). Whether schizoaffective disorder is a variant of schizophrenia (as in DSM-5 and ICD-10 classification systems), a variant of bipolar disorder, or part of a dimensional continuum between psychotic depression, bipolar disorders and schizophrenia is currently being investigated.

Research into the assessment and treatment of schizoaffective disorder will rely less on DSM and ICD criteria as time progresses, and more on the dimensional Research Domain Criteria currently being developed by the U.S. National Institute of Mental Health (NIMH). The Research Domain Criteria initiative, led by Bruce Cuthbert, Ph.D., of NIMH, is the inspiration for the Roadmap for Mental Health Research in Europe (ROAMER). The purpose of the Research Domain Criteria initiative is to address the marked variability and overlap within and among the disorder categories, and to foster development of more effective assessment and treatment for each individual patient. Over the coming decades, advances resulting from the Research Domain Criteria in the U.S. and ROAMER in Europe will be incorporated into future versions of the DSM and ICD, with the hope of eventually leading to personalized mental health of greater diagnostic accuracy and with more targeted and useful treatments, including biomedical, psychosocial, and possibly preventive approaches.