Have you heard the saying “Things come in three’s?” Well, that was the case this month when over a three week period, I was asked the following question three times, at three separate Asian community health events “Which type of dementia is more common in Asians — Alzheimer’s disease or vascular dementia?”
A similar question was posed in a recently published study that sought to examine the trends in prevalence (existing cases) of dementia, Alzheimer’s disease and vascular disease from a Japanese population sample. Participants came from the town of Hisayama, which has had a stable population for the last 50 years, has similar age distributions, occupational status and nutrient intake almost identical to that of the rest of Japan. A total of four examinations for dementia were conducted on all persons 65 years or older between 1985 and 2005. Researchers reported that over 20 years, the prevalence of dementia (adjusted for age and sex) significantly increased with time — from 6.0 percent in 1985 to 8.3 percent in 2005. A similar trend was also noted for Alzheimer’s disease (1.1 percent in 1985 to 3.8 percent in 2005) but not for vascular dementia. Further, the prevalence of Alzheimer’s disease was more likely to increase in those 75+ years or older.
This study nicely demonstrates that in Japan, a country that has one of the highest ratios of elderly persons to the general population, not only is the prevalence of dementia increasing but also that of Alzheimer’s disease. Further studies will be needed to examine whether these trends are similar for the other Asian populations that are in the region.
Here are three articles you can refer to, to learn about this particular study or the Hisayama study in general.
- Sekita A, Ninomiya T, Tanizaki Y et al. Trends in prevalence of Alzheimer’s disease and vascular dementia in a Japanese community: the Hisayama Study, Acta Psychiatr Scand 2010.
- Tanizaki Y, Kiyohara Y, Kato I, et al. Incidence and risk factors for subtypes of cerebral infarction in a general population. The Hisayama Study. Stroke 2000.
- Yoshitake T Kiyohara Y, Kato I et al. Incidence and risk factors for vascular dementia and Alzheimer’s disease in a defined Japanese population: the Hisayama Study. Neurology 1995.
Thanks for reading.