In Japan, where the population is aging, it is necessary to maintain mental and physical health over the long term in order to solve social problems such as increasing medical expenses. It has been suggested that exposure to cold adversely affects brain health. Thus, we hypothesized that the brain health of residents in cold houses would be worse than that of residents in warm houses. In the winter season from 2016 to 2017, we measured indoor temperature, conducted brain health tests using MRI examination, and administered questionnaire surveys for 59 residents of a town in northern Japan. The results of multiple regression analysis show that residents who had a cold living room had lower indexes representing the quality of cranial nerve fibers than residents who had a warm living room in winter.