Clinical presentation of late-onset schizophrenia.

DSM-III-R defines late-onset schizophrenia as schizophrenia that begins after age 45. The authors describe five patients who met DSM-III-R criteria for this disorder. The characteristic features of the disorder include bizarre delusions (usually of a persecutory nature), auditory hallucinations, a history of normal functioning at least until age 45, and a deterioration in personal-social functioning after the onset of illness. Physical examination, routine laboratory tests, neuropsychological evaluation, and magnetic resonance imaging (MRI) scans did not suggest the presence of any diagnosable organic mental disorder. In each of the five cases, mood disorders, delusional (paranoid) disorder, and schizophrenia with onset before age 45 were also considered in the differential diagnosis and ruled out. The authors' case vignettes support the premise that late-onset schizophrenia is a clinically diagnosable entity. Cautions in the diagnosis and treatment of such patients are discussed.