No neuropathologic evidence for an increased frequency of Alzheimerʹs disease among elderly schizophrenics

Background: There is currently controversy as to the frequency of Alzheimerʹs disease (AD) in elderly persons with schizophrenia. Several studies have reported an increased frequency of AD in elderly schizophrenics, whereas others have found no increase. This issue is important because it has been hypothesized that medications used to treat schizophrenia may exacerbate AD histopathology. Methods: We examined autopsy cases from a state psychiatric hospital and a Veterans Affairs medical center. Charts were reviewed on 166 subjects to determine if the history warranted a DSM-IV diagnosis of schizophrenia. All subjects had complete gross and microscopic neuropathologic evaluations, which were reviewed for evidence of Alzheimerʹs disease. Results: Retrospective chart review identified 51 subjects over the age of 55 who met DSM-IV criteria for schizophrenia (mean age = 71.7 years, SD = 8.6, range 56–95 years). Of these 51, only 1 met neuropathologic criteria for AD, a frequency of 2%. Conclusions: The frequency of subjects meeting neuropathologic criteria for Alzheimerʹs disease in our sample of schizophrenics was equal to or less than that found in the general population. Because institutionalized populations may contain an excess of elderly schizophrenic patients with severe behavioral pathologies, which may in turn reflect the presence of neurodegenerative processes such as Alzheimerʹs disease, our results may actually overestimate the frequency of Alzheimerʹs in the entire schizophrenic population. The frequency of Alzheimerʹs disease in the elderly with schizophrenia may be less than that in the general population.