Decomposition of gender differences in cognitive functioning: National Survey of the Japanese elderly

Background: It is well known that females generally live longer than males, but women tend to suffer from more illnesses and limitations than men do, also for dementia. However, limited empirical evidence is available why this 'male-female health-survival paradox' is observed. This study aimed to investigate factors which account for gender differences in health, particularly cognitive functioning and decline among older adults. Methods: Data were retrieved from the National Survey of the Japanese Elderly, which is a longitudinal survey of a nationwide representative sample of Japanese adults aged 60 or over. Gender differences in cognitive functioning and decline in three-year follow-ups were decomposed using Blinder-Oaxaca decomposition analysis, regarding demographic, socioeconomic, and health-related factors into the 'explained' component, by differences in individual attributes listed above, and the 'unexplained' component. Results: Empirical analyses showed that women's lower cognitive functioning was partly explained by the endowment effect. Moreover, a shorter duration of formal education and a larger proportion with their longest occupation being domestic worker accounted for steeper cognitive decline and more prevalent mild cognitive impairment in women than in men. Conclusion: This empirical study suggested that gender differences in cognitive functioning and decline account for different individual attributes of social determinants among men and women. Particularly, men seem to be more engaged in activities which accumulate intellectual experiences through education and occupation, as suggested by the cognitive reserve hypothesis.