Elderly Japanese emigrants to Brazil before World War II: II. Prevalence of senile dementia

Background We previously showed the prevalence of dementia in the town of T ajiri (Miyagi Prefecture, Japan), and found it to be 8.0%. The first popula tion-based study on dementia in Brazil (Catanduva) disclosed the prevalence as being 7.1%. To evaluate the effects of environment on development of de mentia, elderly Japanese immigrants living in Brazil were examined. Brazil is the country with the largest number of Japanese immigrants. Methods All immigrants aged 65 years and over from Miyagi Prefecture, livin g in the four cities of the Sao Paulo Metropolitan area were targeted (n = 192). We were able to examine 166 subjects (86.5%). The diagnosis of dement ia was based on the DSM-IV with the severity assessed by the CDR (clinical dementia rating) scales. The cognitive ability screening instrument (CASI) was used for neuropsychological assessment. Results Thirteen subjects were diagnosed with dementia, CDR 1-3, the preval ence being 7.8%. Older subjects suffered more from dementia, and, paradoxic ally, the more highly educated subjects also suffered more. All the CASI it ems, except for long-term memory and visual construction, significantly det eriorated in the CDR 0.5 group compared with the CDR 0 group. Comments The prevalence of dementia was not thought to be affected by envir onmental factors. A paradoxically higher rate of dementia in the more educa ted subjects was probably due to the historical problems of the immigrants. Intact CASI item long-term memory in the CDR 0.5 group indicated that susp ected dementia patients could maintain this function. This is the first epi demiological study on dementia in elderly Japanese immigrants in Brazil. Co pyright (C) 2001 John Wiley & Sons, Ltd.