Schizophreniform disorder and brief psychotic disorder. These disorders are of shorter duration than schizophrenia as specified in Criterion C, which requires 6 months of symp- toms. In schizophreniform disorder, the disturbance is present less than 6 months, and in brief psychotic disorder, symptoms are present at least 1 day but less than 1 month.
Delusional disorder. Delusional disorder can be distinguished from schizophrenia by the absence of the other symptoms characteristic of schizophrenia (e.g., delusions, prom- inent auditory or visual hallucinations, disorganized speech, grossly disorganized or cata- tonic behavior, negative symptoms).
Schizotypal personality disorder. Schizotypal personality disorder may be distinguished from schizophrenia by subthreshold symptoms that are associated with persistent person- ality features.
Obsessive-compulsive disorder and body dysmorphic disorder. Individuals with obsessive-compulsive disorder and body dysmorphic disorder may present with poor or absent insight, and the preoccupations may reach delusional proportions. But these disorders are distinguished from schizophrenia by their prominent obsessions, compul- sions, preoccupations with appearance or body odor, hoarding, or body-focused repeti- tive behaviors.
Posttraumatic stress disorder. Posttraumatic stress disorder may include ﬂashbacks that have a hallucinatory quality, and hypervigilance may reach paranoid proportions. But a trau- matic event and characteristic symptom features relating to reliving or reacting to the event are required to make the diagnosis.
Autism spectrum disorder or communication disorders. These disorders may also have symptoms resembling a psychotic episode but are distinguished by their respective defi- cits in social interaction with repetitive and restricted behaviors and other cognitive and communication deficits. An individual with autism spectrum disorder or communication disorder must have symptoms that meet full criteria for schizophrenia, with prominent hallucinations or delusions for at least 1 month, in order to be diagnosed with schizophre- nia as a comorbid condition.
Other mental disorders associated with a psychotic episode. The diagnosis of schizo- phrenia is made only when the psychotic episode is persistent and not attributable to the physiological effects of a substance or another medical condition. Individuals with a de- lirium or major or minor neurocognitive disorder may present with psychotic symptoms, but these would have a temporal relationship to the onset of cognitive changes consistent with those disorders. Individuals with substance/medication-induced psychotic disorder may present with symptoms characteristic of Criterion A for schizophrenia, but the sub- stance/medication-induced psychotic disorder can usually be distinguished by the chron- ological relationship of substance use to the onset and remission of the psychosis in the absence of substance use.
Rates of comorbidity with substance-related disorders are high in schizophrenia. Over half of individuals with schizophrenia have tobacco use disorder and smoke cigarettes regularly. Comorbidity with anxiety disorders is increasingly recognized in schizophre- nia. Rates of obsessive-compulsive disorder and panic disorder are elevated in individuals with schizophrenia compared with the general population. Schizotypal or paranoid per- sonality disorder may sometimes precede the onset of schizophrenia.
Life expectancy is reduced in individuals with schizophrenia because of associated medical conditions. Weight gain, diabetes, metabolic syndrome, and cardiovascular and pulmonary disease are more common in schizophrenia than in the general population.
Poor engagement in health maintenance behaviors (e.g., cancer screening, exercise) in— creases the risk of chronic disease, but other disorder factors, including medications, life- style, cigarette smoking, and diet, may also play a role. A shared vulnerability for psychosis and medical disorders may explain some of the medical comorbidity of schizo- phrenia.