[Dementia and lifestyle-related diseases in Japanese aging society]

Recently, the number of elderly patients with dementia has been increasing in Japan because of both the extension of average life expectancy and a considerable rise in the incidence of dementia with age. For these reasons, dementia in Japan has become common, and more than half of all cases are Alzheimer disease. This disease has typically been considered to be a degenerative disorder due to genetic abnormalities, but recent epidemiological studies have indicated that lifestyle-related diseases such as hypertension, diabetes, dyslipidemia, and obesity in midlife could accelerate the dementing process, via either vascular changes in cerebral infarction or Alzheimer-related pathological changes with plaque and tangle formations which result in dementia in later life. Furthermore, several studies have suggested that a high intake of vegetables and fish, an active daily life, and lifelong education might positively influence cognitive function as neuroprotective factors. Therefore, we should try to prevent dementia based on the clinical and hygienic management of the lifestyles and lifestyle-related diseases, even in the youth.