Psychosis is a syndrome associated with dysregulation of the neurotransmitters dopamine and serotonin, and abnormal functioning of key brain circuits, particularly involving frontal, temporal, and mesostriatal brain regions. People with psychosis typically experience hallucinations (e.g., auditory, visual, tactile), delusions, and disorganised thoughts and actions.
Psychosis can be due to primary (“non-organic”) psychiatric disorders or can be secondary to substance use or specific medical (“organic”) aetiologies. Primary psychotic disorders include schizophrenia, delusional disorder, schizoaffective disorder, schizophreniform disorder, and brief psychotic disorder. A psychotic syndrome may also accompany other psychiatric conditions such as major depressive disorder and bipolar disorder. Patients with psychosis associated with psychiatric disorders present with a combination of hallucinations (mostly auditory), delusions, and disorganised thought process, but are usually oriented and have minimal overt cognitive deficits. With the exception of acute agitation, patients with psychosis (who are otherwise healthy) tend to have normal vital signs. Patients with psychosis secondary to drug use or medical causes often present with altered vital signs, visual hallucinations, and severe cognitive impairment, including confusion or disorientation.
The assessment of psychosis includes a physical examination, a complete psychiatric and medical history, and a laboratory work-up. The physical examination should include a detailed neurological examination and a complete mental status examination, with the following areas of focus: mood and affect, thought process and content (including an assessment of delusions, abnormal perceptions, suicidal and homicidal ideation, and insight), and a cognitive examination.
The medical history should include a review of head injury, seizures, cerebrovascular disease, sexually transmitted infections, and new or worsening headaches. Collateral history is recommended to chart the onset and course of the psychosis.
Recommended initial laboratory work-up includes a complete blood count, comprehensive metabolic profile, thyroid function tests, urine toxicology, and measurement of parathyroid hormone, calcium, vitamin B12, folate, and niacin. Based on clinical suspicion, testing for HIV infection and syphilis, as well as brain neuroimaging (e.g., CT or MRI), should be considered as part of the initial work-up.
The lifetime prevalence of psychosis in the general population is about 3%, with 0.21% of cases attributable to medical conditions. Most commonly, psychotic symptoms are associated with other mental disorders. The lifetime prevalence of schizophrenia is approximately 0.3%–0.7%. In one urban primary care population study, 20.9% of adult patients reported 1 or more psychotic symptoms; psychosis co-occurred with depressive, anxiety, and panic disorders, and substance use disorders. One cross-sectional study found that the rates of positive symptoms of psychosis occurring during acute mood episodes of bipolar disorder (BD) (mania, depression, and mixed states) is similar to the rates observed in schizophrenia. The rate of peripartum psychosis, which is a type of brief psychotic disorder, is 1 to 2 per 1000 childbirths; risk factors include a history of depression, bipolar disorder, or past peripartum psychosis or mood disorder.
- Schizoaffective disorder
- Brief psychotic disorder
- Schizophreniform disorder
- Depression with psychotic features
- Bipolar disorder
- Delusional disorder
- Withdrawal syndrome
- Inhalants (solvents, aerosols, gases, nitrites)
- Chronic thiamine deficiency (Korsakoff's psychosis)
- Acute hepatic porphyria
- Delusional symptoms in partner of individual with delusional disorder (folie a deux)
- Organophosphate toxicity
- Dopamine agonists
- Other prescription or over-the-counter medications
- Heavy metal toxicity
- Traumatic brain injury
- Brain tumour
- Multiple sclerosis
- Encephalitis (infective or autoimmune)
- Delirium with psychosis
- Vitamin B12 deficiency
- Folate deficiency
- Niacin deficiency
- Cushing's syndrome
- Thyroid dysfunction
- Lupus cerebritis
- Wilson's disease
- Lysosomal storage disease
- Metachromatic leukodystrophy
- Klinefelter's syndrome
- DiGeorge syndrome
- Prader-Willi syndrome
- International classification of diseases, 11th revision (ICD-11)
- Diagnostic and statistical manual of mental disorders, fifth edition, text revision (DSM-5-TR)
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