Text adapted from "The patient with Psychosis" in Psychiatry in primary care by George Foussias and Z. Jeff Daskalakis (CAMH, 2019).
Specific psychotic disorders
Brief psychotic disorder: characterized by psychotic symptoms lasting at least one day, but less than one month.
Schizophreniform disorder: characterized by symptoms of schizophrenia that last at least one month, but less than six months.
Delusional disorder: characterized by non-bizarre delusions and the absence of other characteristic symptoms of schizophrenia (e.g., hallucinations, negative symptoms, disorganized speech or behaviour).
Schizoaffective disorder: characterized by a mood episode that is concurrent with psychotic symptoms of schizophrenia, where the mood symptoms are present for a substantial portion of the total duration of the disturbance and psychotic symptoms are present for at least two weeks in the absence of prominent mood symptoms.
Schizophrenia: characterized by the presence of symptoms (e.g., hallucinations, delusions, negative symptoms, disorganized speech or behaviour) for at least six months.
Other psychiatric disorders
Psychosis may be a feature of other psychiatric disorders and states, including:
- delirium or dementia
- substance intoxication or withdrawal
- mood disorder with psychotic features. Mood disorder with psychotic features can be differentiated from schizophrenia by the appearance of psychotic symptoms only during periods of mood disturbance.
Many physical illnesses can cause psychotic symptoms, but they generally have other symptoms and signs associated with the primary disease.
For first presentations of psychosis, conduct a physical examination, including a neurological examination, and a general medical history and review of symptoms. Subsequent laboratory investigations should be ordered based on the history or physical examination results.
A toxicology screen could be used where clinically indicated to rule out substance intoxication and withdrawal that can present with psychotic symptoms.
For patients presenting for the first time with psychotic symptoms, a CT or MRI is recommended only if clinically indicated based on the history, neurological examination or results of neuropsychological testing.