Section Learning Objectives

• Indicate the prevalence of schizophrenia spectrum and other psychotic disorders.
• Describe the sex ratios for these disorders.
• Identify the disorders that are commonly comorbid with schizophrenia spectrum and other psychotic disorders.

8.2.1 Epidemiology

Schizophrenia occurs in approximately 0.3%-0.7% of the general population (APA, 2022). There is some discrepancy between genders related to the emphasis on various symptoms. For example, men typically present with more negative symptoms and disorganization whereas women present with more mood-related and psychotic symptoms. Despite gender differences in the presentation of symptoms, there appears to be an equal risk for both genders to develop the disorder.

Schizophrenia typically occurs between late teens and mid-30s, with the onset of the disorder typically occurring slightly earlier for men than for women (APA, 2022). Specifically, the peak age of onset is early-to-mid 20s for men and late-20s for women. Earlier onset of the disorder is generally predictive of a worse overall prognosis. The onset of symptoms is typically gradual, with initial symptoms presenting similarly to depressive disorders; however, some individuals will present with an abrupt presentation of the disorder. Negative symptoms appear to be more predictive of a poorer prognosis than other symptoms. This may be due to negative symptoms being the most persistent, and therefore, most difficult to treat or to the effects of avolition on functioning. Overall, an estimated 20% of individuals who are diagnosed with schizophrenia report complete recovery of symptoms (APA, 2013).

Schizoaffective disorder, schizophreniform disorder, brief psychotic disorder, and delusional disorder prevalence rates are all significantly less than that of schizophrenia, occurring in less than 0.3% of the general population. While schizoaffective disorder is diagnosed more in women than men, schizophreniform disorder and delusional disorder appear to be diagnosed equally between genders. The gender discrepancy in schizoaffective disorder is likely due to the higher rate of the depressive type in women because this sex discrepancy is not evident in the bipolar type of schizoaffective disorder (APA, 2022).

8.2.2 Comorbidity

There is a high comorbidity rate between schizophrenia spectrum and other psychotic disorders and substance use disorders. Furthermore, there is some evidence to suggest that the use of various substances (especially the use of cannabis in adolescence) may place an individual at an increased risk to develop a psychotic disorder if a genetic predisposition is also present (Corcoran et al., 2003). Additionally, there appears to be an increase in anxiety and obsessive-compulsive disorders—specifically OCD and panic disorder—among individuals with schizophrenia compared to the general public.

It should also be noted that individuals diagnosed with a schizophrenia spectrum and other psychotic disorder are also at an increased risk for associated medical conditions such as weight gain, diabetes, metabolic syndrome, and cardiovascular and pulmonary disease (APA, 2013). This predisposition to various medical conditions is likely related to medications and poor lifestyle choices, and also places individuals at risk for a reduced life expectancy.