Incidence and risk factors of vascular dementia and Alzheimer's disease in a defined elderly Japanese population

Abstract

We followed 828 nondemented residents of Hisayama Town, Kyushu, Japan, aged 65 years or older (88.3% of the elderly population) for 7 years starting in 1985 in order to determine the type-specific incidence of dementia and its risk factors in the general Japanese population. Only two subjects were lost to the follow-up, during which period 103 subjects developed dementia. Morphologic examination of the brains of 89 subjects (86.4%) was made by autopsy or CT. We made the initial diagnosis of dementia based on the DSM-III-R criteria, with the diagnoses of vascular dementia (VD) being based on the NINDS-AIREN criteria and Alzheimer's disease (AD) on the NINCDS-ADRDA criteria. The incidence of VD and AD increased with age for both sexes. The age-adjusted total incidence (per 1,000 person-years) of dementia was 19.3 for men and 20.9 for women. The corresponding rates for VD were 12.2 for men and 9.0 for women, and for AD, 5.1 for men and 10.9 for women. Among the VD subjects whose brain morphology we examined, the most frequent type of stroke was multiple lacunar infarcts (42%), but half these subjects lacked a stroke episode in their histories. Multivariate analysis showed that age, prior stroke episodes, systolic blood pressure, and alcohol consumption were significant independent risk factors for the occurrence of VD. In contrast, age and a low score on Hasegawa's dementia scale were significant risk factors for AD, and physical activity was a significant preventive factor for AD.(ABSTRACT TRUNCATED AT 250 WORDS)

Cognitive reserve: Implications for diagnosis and prevention of Alzheimer’s disease

“…Nevertheless, many other cohorts have reported that physical activities provide protection for future cognitive decline [8,32,[52][53][54][55][56]. In addition, high levels of physical activity were associated with reduced risk of dementia in at least four prospective studies [21,[57][58][59]. Decreased risk for cognitive decline has been reported not only for strenuous [32] but also moderate physical activities [55,57].…”

Cerebral complications of hypertension

“…104,[116][117][118] A significant correlation with hypertension exists in all forms of vascular dementia. [118][119][120][121] Other risk factors include increasing age, 122 low education, 123 coronary heart disease, 122,124 atrial fibrillation, 125 diabetes, [126][127][128] transient ischaemic attacks and cerebrovascular accidents, 124 high hematocrit level 120 and smoking. 126 …”

“…94,132,133 In the Hisayama study, hypertension was a risk factor for vascular dementia but not for Alzheimer's disease; the 7-year incidence of vascular dementia decreased in men, along with progress in antihypertensive treatment in Japan, while the prevalence of Alzheimer's disease remained unchanged in men and women suggesting that hypertension does not play a major role in the pathogenesis of Alzheimer's disease in Japanese. 120 In contrast, in Western populations, several studies have suggested that hypertension may play a role in the development of Alzheimer's disease. 118,134 Alzheimer's disease has been reported to be associated with other vascular risk factors 115,135 including coronary heart disease, 136 atrial fibrillation, 125 diabetes mellitus, 127 and white matter lesions.…”

“…Furthermore this relationship may actually be underestimated since asymptomatic stroke may be a significant factor in the development of dementia. 120 Several studies have also shown that subtle cognitive changes without dementia are also frequently observed early after stroke. 139,142 However, unrecognised pre-stroke dementia may contribute to the apparent onset of dementia after an ischaemic stroke and lead to an overestimation of the incidence of so-called poststroke dementia.…”

Body mass index and stroke incidence in a Japanese community: the Hisayama study

“…Stroke is a leading cause of death 1 and permanent disability in middleaged and elderly people in Japan [2][3][4] as well as in other developed countries. 5 In Japan, the prevalence of obesity has increased rapidly along with the westernization of lifestyle, 6 although it remains considerably lower than that in Western populations.…”