Late-life overweight, obesity may protect against Alzheimer’s

Body mass index (BMI) in later adulthood appears to be inversely correlated with the incidence of Alzheimer’s disease (AD), a recent study has found. Older adults who are overweight or obese see lower AD risks.

The study included 148,534 individuals aged ≥65 years who had participated in the 2002–2005 screening programme under the Korean National Health Insurance Service. Over 10 years of follow-up, 22,279 patients developed incident AD.

Cox proportional hazards analysis revealed a significant and inverse correlation between BMI and AD risk. Compared to those who were of normal weight (BMI 18.5–22.9 kg/m²), underweight (BMI <8.5 kg/m²) adults were nearly 20 percent more likely to develop AD (hazard ratio [HR], 1.17, 95 percent confidence interval [CI], 1.09–1.24).

This remained true even when underweight participants were divided into the following subgroups: mildly thin (HR, 1.13, 95 percent CI, 1.05–1.22), moderately thin (HR, 1.25, 95 percent CI, 1.09–1.44), and severely thin (HR, 1.24, 95 percent CI, 1.02–1.51; p_trend<0.001).

In contrast, those who were overweight (BMI 23.0–24.9 kg/m²; HR, 0.90, 95 percent CI, 0.87–0.93) or obese (BMI ≥25.0 kg/m²; HR, 0.83, 95 percent CI, 0.80–0.85) were at a significantly lower risk of AD (p_trend<0.001).

“These results suggest that improving public nutritional status to prevent weight loss in older adults may be a key strategy for reducing the incidence of AD,” the researchers said.