We investigated the relationship between lifestyle and cognitive function in elderly subjects who had their checkups at a memory clinic. The 136 elderly study subjects included 51 with Alzheimer’s disease, 22 with vascular dementia, 23 with frontotemporal dementia, 25 with mild cognitive impairment, and 15 healthy control. The patients’ lifestyles were assessed using the Frenchay activities index (FAI), and their cognitive functions were assessed by neuropsychological tests, such as the mini-mental status examination and the frontal assessment battery (FAB). The FAI score was lower in the demented patients than in the control subjects. Strong correlations were observed between the FAI scores and the scores in the neuropsychological tests. The FAI scores did not correlate with the educational level or the duration of disease. The fi ndings from the stepwise regression analysis indicated that the FAB score, the number of family members, gender, and age were factors independently affecting the FAI score. The results indicated that the lifestyles of the elderly people might be affected by not only their age and family organization but also their cognitive function. We concluded that cognitive function could play a role in the lifestyle of elderly people.