Sex Differences in the Relation Between Subjective Memory Complaints, Impairments in Instrumental Activities of Daily Living, and Risk of Dementia

Background: Older people with subjective memory complaints (SMC) and Instrumental Activities of Daily Living impairments (IADL-I) have an increased risk of developing dementia. Previous reports suggest that the predictive value of SMC and IADL-I may differ between sexes, leaving possible consequences for personalized risk prediction and prognosis. However, none of these studies addressed the competing risk of death, which may substantially differ between sexes. Objective: We investigated sex-differences in the association between IADL-I, SMC, and incident dementia and mortality as competing risk. Methods: 3,409 community-dwelling older people without dementia (mean age 74.3 +/- 2.5), were followed for 6.7 years (median). Baseline SMC were assessed using the 15-item Geriatric Depression Scale memory question, and IADL-I using the Academic Medical Center Linear Disability Score. Potential sex-differences in the predictive value of SMC and IADL-I were assessed using Cox regression models with an interaction term for sex. Results: HRs for isolated SMC and SMC+ IADL-I and risk of dementia were higher in women (HR: 2.02,95% CI = 0.91-4.46, p = 0.08; HR:2.85, 95% CI = 1.65-4.91, p < 0.001) than in men (HR:1.52, 95% CI = 0.86-2.69, p = 0.18; HR:1.24, 95% CI = 0.62-2.49, p = 0.54), but these sex-differences were not significant. Conversely, HRs for isolated IADL-I and risk of mortality were higher in men (HR:1.56, 95% CI = 1.18-2.05, p = 0.002) than in women (HR:1.14, 95% CI = 0.80-1.62, p = 0.48), but again, these sex-differences were not significant. Conclusion: The predictive value of SMC and IADL-I for the risk of dementia and mortality was not significantly modified by sex. However, the competing risk of death for these factors differed considerably between men and women, suggesting it is an essential factor to consider when comparing sex-differences in IADL/dementia risk.