Prevalence and subtypes of dementia in a rural Chinese population

We conducted a single-stage community-based study of dementia on all regist ered residents greater than or equal to 65 years in age in a rural Chinese community. Neurologists conducted semistructured interviews and examined al l participants; they also interviewed family members in cases where dementi a was suspected. The diagnosis was made by consensus according to the crite ria of the Diagnostic and Statistical Manual of Mental Disorders, 3rd ed, r evised (DSM-III-R). Among the 2,055 contacted individuals, 1,736 (84.5%) pa rticipated in the study and 44 (13 men and 31 women) were diagnosed as havi ng dementia, including 35 (80%) with probable Alzheimer disease (AD) and 3 (7%) with vascular dementia (VsD). The rates of dementia were 0.5% for ages 65-74 years, 2.9% for ages 75-84 years, and 12.0% for ages 85-101 years. T he overall rate was 2.5% for age greater than or equal to 65 years. After c ontrolling for age, neither a lack of formal education nor being a woman wa s a risk factor for dementia. At 2-year follow-up, 30 of the 44 demented pa rticipants had died, yielding a 2-year survival rate of 32%. The present re sults corroborated our previous findings of lower prevalence rates of demen tia among the Chinese than among Western populations, and both genetic and sociocultural factors may have contributed to the low rates. The lack of ne uroradiological imaging studies in the present study may have contributed t o the finding of an unusually low rate of VsD.