Schizoaffective disorder: A challenging diagnosis

Course and outcome

The onset of SAD typically occurs in early adulthood, but can range from childhood to senescence. Approximately one-third of patients are diagnosed before age 25, one-third between age 25 and 35, and one-third after age 35.^21-23 Based on a literature review, Cheniaux et al⁷ concluded that that age at onset for patients with SAD is between those with schizophrenia and those with mood disorders.

The course of SAD is variable but represents a middle ground between that of schizophrenia and the mood disorders. In a 4- to 5-year follow-up,²⁴ patients with SAD had a better overall course than patients with schizophrenia but had poorer functioning than those with bipolar mania, and much poorer than those with unipolar depression. Mood-incongruent psychotic features predict a particularly worse outcome. These findings were reaffirmed at a 10-year follow-up.²⁵ Mood symptoms portend a better outcome than do symptoms of schizophrenia.

The lifetime suicide risk for patients with SAD is estimated at 5%, with a higher risk associated with the presence of depressive symptoms.²⁶ One study found that women with SAD had a 17.5-year reduced life expectancy (64.1 years) compared with a reduction of 8.0 years for men (69.4 years).²⁷

Comorbidity

Patients with SAD are commonly diagnosed with other psychiatric disorders, including anxiety disorders, obsessive-compulsive disorder, posttraumatic stress disorder, and substance use disorders.^21,28,29 When compared with the general population, patients with SAD are at higher risk for coronary heart disease, stroke, obesity, and smoking, likely contributing to their decreased life expectancy.^27,30 Because second-generation antipsychotics (SGAs) are often used to treat SAD, patients with SAD are at risk for metabolic syndrome and diabetes mellitus.³⁰

Clinical assessment

Because there are no diagnostic, laboratory, or neuroimaging tests for SAD, the most important basis for making the diagnosis is the patient’s history, supplemented by collateral history from family members or friends, and medical records. Determining the percentage of time spent in a mood episode (DSM-5 Criterion C) is especially important.³¹ This requires the clinician to pay close attention to the temporal relationship of psychotic and mood symptoms.

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