Public Health

Studies on sex/gender differences in dementia risk have often overlooked racial and ethnic differences, particularly within Asian American communities. Our aim is to compare sex/gender-specific lifetime dementia risk conditional on dementia-free survival to age 60 among Chinese, Filipino, Japanese, South Asian, and non-Latino White older adults in California.

We leveraged a cohort study including mailed surveys linked with electronic health records (EHR) (2002-2020) from Kaiser Permanente Northern California (KPNC). These analyses included survey respondents ages ≥60 years who identified as Chinese, Filipino, Japanese, South Asian, or non-Latino White with at least two years of KPNC coverage and no dementia diagnosis at time of survey. Sex/gender and dementia diagnoses were ascertained from the EHR. We used the Aalen-Johansen estimator to calculate the cause-specific cumulative incidence of dementia conditional on dementia-free survival to age 60 (i.e., lifetime dementia risk), considering death as a competing event, and calculated sex/gender dementia risk differences and risk ratios at ages 75, 80, 85, 90, and 95.

We included 159,477 participants who self-identified as follows: 6,415 as Chinese, 5,020 as Filipino, 3,314 as Japanese, 1,061 as South Asian, and 143,667 as non-Latino White. The proportion of women ranged from 39% (South Asian) to 63% (Japanese); mean baseline age ranged from 68 (South Asian) to 73 years (Japanese). Among women, lifetime dementia risk ranged from 38% (95%CI: 38-39) (Non-Latino White participants) to 49% (95%CI: 40-67) (South Asian participants); among men, lifetime dementia risk ranged from 28% (95%CI: 25-31 Chinese participants; 95%CI: 22-37 South Asian participants) to 35% (95%CI: 30-39) (Japanese participants) (Figure 1). The largest sex/gender differences in lifetime dementia risk were observed among South Asian and Chinese participants (Figure 2). Absolute sex/gender differences in dementia risk emerged at age 80 for South Asian participants, age 85 for Chinese, Japanese, and non-Latino White participants, and age 95 for Filipino participants. Overall, dementia-free mortality was substantially higher for men than women.

Lifetime dementia risk conditional on dementia-free survival to age 60 was higher among women than men and varied across racial and ethnic groups, potentially driven by differences in mortality and social and structural factors.