[Analysis of dietary factors in Alzheimer's disease: clinical use of nutritional intervention for prevention and treatment of dementia].

To determine dietary factors involved in the pathological process of Alzheimer's disease (AD), we analyzed food consumption and intake of nutrients using Self-administered Diet History Questionnaire (DHQ) developed for Japanese. Sixty four AD patients and 80 age-matched healthy subjects were enrolled in this study. AD was diagnosed according to the criteria of DSM-IV. Dietary behaviors of AD patients was markedly deviated from those of age-matched healthy elderly. AD patients disliked fish and green-yellow vegetables and took more meats than controls. Energy-adjusted analysis of nutrients revealed that AD patients took less vitamin C and carotene. Most conspicuously, AD patients took significantly smaller amount of n-3 polyunsaturated fatty acid (PUFA) reflecting low consumption of fish, and their n-6/n-3 ratio was significantly increased. These habits started from 3 months to 44 years before the onset of dementia, suggesting these dietary abnormalities are not merely the consequence of dementia. Rather, it implies that AD might be a life style-related disease such as coronary heart disease, western style diet-associated cancer and hyperallergy. To see if cognitive function was improved by correcting the n-6/n-3 ratio, we prescribed eicossapentaenoic acid (EPA), one type of n-3 PUFA, for AD patients. Cognitive function was evaluated using MMSE. Administration of EPA (900 mg/day) improved MMSE significantly with maximal effects at 3 months and the effects lasted 6 months. However, the score of MMSE decreased after 6 months. The present study showed that nutritional intervention is useful for the prevention of AD, and also for the therapy of dementia, though it has some limitation.