Incidence of dementia after age 90 years and association with APOE genotype, race, and sex in the USA: the LifeAfter90 prospective cohort study.

内容摘要

Little is known about dementia incidence and its risk factors in people older than 90 years, particularly in heterogeneous populations. We evaluated dementia incidence and examined the associations of sex, race and ethnicity, and APOE genotype with dementia risk after age 90 years using data from LifeAfter90, an ongoing prospective cohort study. LifeAfter90 is a prospective cohort study that enrolled Kaiser Permanente Northern California members, who were at least 90 years old, from the San Francisco Bay Area and Sacramento, USA. Participants were clinically evaluated every 6 months from July 17, 2018, to Nov 9, 2024, in person or remotely. Incident all-cause dementia was diagnosed by a combination of physician assessment, Clinical Dementia Rating, and a Functional Activities Questionnaire. Sex, race and ethnicity, and education were captured during in-person assessments; APOE genotyping was performed using salivary DNA. We estimated age-standardised dementia incidence rates and used age-adjusted Cox and Fine-Gray competing-risk models to study the association between sex, race and ethnicity, APOE genotype, and dementia. The Fine-Gray subdistribution hazard ratio (sHR) models treated death as a competing risk. Models were adjusted for age (time-scale) and individuals were followed until dementia diagnosis or end of follow-up. Of 1120 individuals initially available, 96 with prevalent dementia and 219 with only one clinical evaluation were excluded; 805 participants were included. Median age was 92 years (range 90-103), 494 (61%) were female, 209 (26%) Asian, 191 (24%) African American or Black, 157 (20%) Hispanic or Latinx, 228 (28%) White, and 20 (2%) from other racial or ethnic groups; 413 had APOE data. During mean follow-up of 2 years (SD 1·7), 138 (17%) developed dementia and 295 (37%) died. The age-standardised incidence rate was 116·82 cases per 1000 person-years (95% CI 93·69-139·96). In Fine-Gray models, dementia risk was higher in female than in male participants (subdistribution hazard ratio [sHR] 1·89, 95% CI 1·30-2·76) and Black than Asian participants (sHR 1·75, 1·07-2·88), lower in APOE ε2 carriers than in non-carriers (sHR 0·39, 0·17-0·88), and not significantly higher in APOE ε4 carriers than in non-carriers (sHR 1·51, 0·92-2·47). No significant differences were found by education. Ethnoracial disparities in dementia risk appear to persist after 90 years, and the association between APOE ε4 and dementia might differ by sex. These findings reinforce the importance of dementia screening and surveillance, even among people with exceptional longevity. National Institute on Aging.