Home cooking, cooking skills and dementia requiring long-term care: a population-based cohort study in Japan

Abstract

Background: People have come to rely on restaurants and takeaway foods, and less on cooking at home. We examined the association between home cooking and dementia incidence, ascertained through administrative long-term care records, and whether the benefits of home cooking differ by cooking skills. Methods: Participants in the Japan Gerontological Evaluation Study, a population-based cohort study, were followed for 6 years. The incidence of dementia was ascertained in 10 978 participants through data from the public long-term care insurance system, which captures functionally significant cognitive impairment requiring care. Cooking frequency and skills were assessed in a baseline survey. Participants with high and low frequencies of home cooking were matched in men and women based on demographic, socioeconomic and health-related factors using propensity score matching. Fine-Grey competing risk models were used, with death treated as a competing event. Results: During the follow-up, 1195 dementia cases were found. A total of 1347 male and 321 female pairs were matched between high (at least once a week) and low (less than once a week) cooking frequencies. The subdistribution hazard ratio (SHR) for high cooking frequency (vs low cooking frequency) was 0.77 (95% CI 0.61 to 0.98) in men and 0.73 (95% CI 0.54 to 0.98) in women. The benefits of higher cooking frequency were more pronounced in those with low cooking skills (SHR 0.33, 95% CI 0.13 to 0.84). Conclusions: Creating an environment where people can cook meals when they are older may be important for the prevention of dementia.