Conversion to dementia from questionable dementia in an ethnic Chinese population.

We investigated the conversion rate and the risk factors for conversion to dementia from questionable dementia in 124 ethnic Chinese subjects with questionable dementia at a memory clinic of a university hospital. They were evaluated annually based on cognitive testing, the clinical dementia rating scale, and a psychiatrist's interview for depression and anxiety. Apolipoprotein E genotyping was performed on 111 of these questionable dementia subjects. All subjects were evaluated at least twice during the follow-up period of 20.4 +/- 12.4 months. During that period, 42 questionable dementia subjects were diagnosed as having Alzheimer's disease, with an annual conversion rate to dementia of 19.9%. Compared with the 82 nonconverters, the 42 converters were significantly older, had lower cognitive, depression, and anxiety scores, and a higher frequency of the apolipoprotein E epsilon 4 allele. Cox regression analysis revealed that the Alzheimer's disease converters had lower scores for orientation, short-term memory, and anxiety, and a higher frequency of the apolipoprotein E epsilon 4 allele than the nonconverters.