No increased incidence of Alzheimer's disease in elderly schizophrenics

There is currently controversy as to the morphological basis of cognitive i mpairment in elderly schizophrenics. In contrast to previous findings, rece nt studies have found no increased frequency of Alzheimer's disease (AD) pa thology in elderly schizophrenics. We examined 99 consecutive autopsy cases of patients over the age of 55 years from a psychiatric hospital who met t he DSM-III-R and ICD.10 criteria for schizophrenia (mean age 69.5 +/- 8.25 years; mean duration of illness 35.15 +/- 10.1 years), 56% showing moderate to severe dementia. All brains were blindly reviewed for evidence of AD us ing CERAD criteria and Braak staging of neuritic AD lesions. "Definite" AD (CERAD C, Braak stage V) was seen in 2 cases aged 56 and 67 years, respecti vely [2% of total or 1/68 (1.4%) of those over age 65]. "Probable" AD (CERA D B, Braak stages IV-V) were seen in 5 cases aged 71-89 years (mean 79 year s; 5% of total or 7.3% of those over age 65), and 1 case each with multiple cerebral infarcts and with Parkinson's disease pathology. In addition, 2 f emales aged 82 and 89 years, respectively, revealed senile dementia with ta ngles (NIA, CERAD negative; Braak stage IV), 1 with hippocampal sclerosis. The total incidence of definite and probable AD in this cohort was 7.1% or 8.7% for those over age 65. This is in line with other recent studies showi ng that the frequency of AD in elderly schizophrenics may be equal or even less than in the general population. The reasons for this negative associat ion and the basis of cognitive deficits in elderly schizophrenics - those w ith dementia usually showing significantly lower brain weight - await furth er elucidation.