Body mass index changes and trajectories from midlife to late-life: association with subjective cognitive complaints in a 30-year Women's cohort study

Background: The relationship between body mass index (BMI) changes across the lifespan and cognitive health in later life remains unclear. This study evaluated the association between BMI changes from midlife to late-life and subsequent subjective cognitive complaints (SCCs) in women. Methods: We analysed data from 5160 women in the New York University Women’s Health Study, a prospective cohort with over 30 years of follow-up. BMI was calculated using self-reported height and weight at baseline and follow-up. SCCs were assessed using a validated questionnaire in 2018–2020. Odds ratios (ORs) for reporting ≥2 SCCs were estimated using unconditional logistic regression. Results: BMI at specific life stages was not significantly associated with SCC risk. BMI changes from midlife to late-life were associated with SCC risk. Compared to women with stable BMI (≤5% change), moderate BMI loss (5.1–10% decrease) was associated with higher odds of ≥2 SCCs (OR: 1.23, 95% CI: 1.02–1.48), large BMI gain (>10% increase) was associated with lower odds of ≥2 SCCs (OR: 0.81, 95% CI: 0.67–0.97). These findings were consistent across sensitivity analyses, including varying age cut-offs and excluding BMI changes occurring 5–10 years before late-life. Conclusions: Our findings emphasize the importance of considering lifelong weight changes in assessing cognitive health risks. In particular, significant weight loss from midlife to late-life may serve as a potential indicator of cognitive decline in older adults. Further research is needed to elucidate the underlying mechanisms of this association and to explore effective interventions for mitigating cognitive health risks.