Is late-onset schizophrenia a subtype of schizophrenia?

Objective: To determine whether late-onset schizophrenia (LOS, onset after age 40) should be considered a distinct subtype of schizophrenia. Method: Participants included 359 normal comparison subjects (NCs) and 854 schizophrenia out-patients age > 40 (110 LOS, 744 early-onset schizophrenia or EOS). Assessments included standardized measures of psychopathology, neurocognition, and functioning. Results: Early-onset schizophrenia and LOS groups differed from NCs on all measures of psychopathology and functioning, and most cognitive tests. Early-onset schizophrenia and LOS groups had similar education, severity of depressive, negative, and deficit symptoms, crystallized knowledge, and auditory working memory, but LOS patients included more women and married individuals, had less severe positive symptoms and general psychopathology, and better processing speed, abstraction, verbal memory, and everyday functioning, and were on lower antipsychotic doses. Most EOS-LOS differences remained significant after adjusting for age, gender, severity of negative or deficit symptoms, and duration of illness. Conclusion: Late-onset schizophrenia should be considered a subtype of schizophrenia.