糖尿病と認知症の疫学

Epidemiology of Diabetes and Risk of Dementia

日本人における糖尿病と認知症発症の関係を明らかにするために，1988年の久山町健診を受診した認知症のない高齢住民全員に75g経口糖負荷試験を実施して耐糖能レベルを正確に評価し，15年間前向きに追跡した。多変量解析でその他の危険因子を調整した結果，糖尿病は認知症，特にアルツハイマー病発症の有意な危険因子であった。認知症の社会的負担を軽減するうえで，増え続ける糖尿病の予防と適切な管理が重要と考えられる。

Abstract

The association between diabetes and the risk of developing dementia has received much attention in epidemiological studies. An accurate population-based prospective cohort study has been conducted in the elderly population of the town of Hisayama in Japan since 1985 aiming to elucidate the secular trends in the prevalence of dementia and examine risk and protective factors for dementia in the Japanese population. The prevalence of all-cause dementia significantly increased from 1985 to 2012. In regard to subtypes of dementia, a similar trend was observed for Alzheimer's disease (AD). In a prospective study of risk factors for dementia in Hisayama elder residents without dementia, diabetes was identified as a significant risk factor for developing all-cause dementia, especially AD. Moreover, 2-hour post-load glucose levels were closely associated with increased risk of all-cause dementia, AD, and vascular dementia. In a pathological study of Hisayama residents, higher levels of 2-hour post-load glucose, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) were significantly associated with increased risk of neuritic plaques. The steep increase in the frequency of diabetes could lead to the increasing trend in the prevalence of dementia, especially AD, in the Japanese elderly.