Schizoaffective disorder: A challenging diagnosis
Paying close attention to the temporal relationship of psychotic and mood symptoms is key.
Differential diagnosis
The differential diagnosis for SAD is broad because it includes all of the possibilities usually considered for major mood disorders and for psychotic disorders5:
- schizophrenia
- bipolar disorder with psychotic features
- major depressive disorder with psychotic features
- depressive or bipolar disorders with catatonic features
- personality disorders (especially the schizotypal, paranoid, and borderline types)
- major neurocognitive disorders in which there are mood and psychotic symptoms
- substance/medication-induced psychotic disorder
- disorders induced by medical conditions.
With schizophrenia, the duration of all episodes of a mood syndrome is brief (<50% of the total duration of the illness) relative to the duration of the psychotic symptoms. Although psychotic symptoms may occur in persons with mood disorders, they are generally not present in the absence of depression or mania, helping to set the boundary between SAD and psychotic mania or depression. As for personality disorders, the individual will not have a true psychosis, although some symptoms, such as feelings of unreality, paranoia, or magical thinking, may cause diagnostic confusion.
Medical conditions also can present with psychotic and mood symptoms and need to be ruled out. These include psychotic disorder due to another medical condition, and delirium. A thorough medical workup should be performed to rule out any possible medical causes for the symptoms.
Substance use should also be ruled out as the cause of the symptoms because many substances are associated with mood and psychotic symptoms. It is usually clear from the history, physical examination, or laboratory tests when a medication/illicit substance has initiated and maintained the disorder.
Neurologic conditions. If a neurologic condition is suspected, a neurologic evaluation may be warranted, including laboratory tests, brain imaging to identify specific anatomical abnormalities, lumbar puncture with cerebrospinal fluid analysis, and an electroencephalogram to rule out a convulsive disorder.
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