Quantifying the Dementia Burden Attributable to Excess Weight in the U.S

Area of Science:

• Gerontology and Geriatric Medicine
• Neuroscience and Neurology
• Public Health and Epidemiology

Background:

• Previous studies on dementia risk and excess weight yielded inconsistent results due to methodological limitations.
• Reverse causality, where early dementia stages might influence weight, poses a significant confounding challenge.

Purpose of the Study:

• To accurately quantify the association between excess weight and dementia risk.
• To mitigate confounding from reverse causality by examining long-term weight history.

Main Methods:

• Utilized a large cohort from the Health and Retirement Study (1992-2018).
• Defined exposure as maximum Body Mass Index (BMI) over a 10-year period preceding follow-up.
• Employed Cox proportional hazards models to assess dementia incidence over 16 years, calculating population attributable fractions.

Main Results:

• Individuals with Class II/III obesity (BMI 35+ kg/m²) faced nearly double the hazard of dementia (aHR 1.89).
• Class I obesity (BMI 30-34.9 kg/m²) and overweight (BMI 25-29.9 kg/m²) were associated with increased dementia hazards of 42% and 22%, respectively.
• An estimated 22.1% of dementia cases could potentially be averted by maintaining normal weight (BMI 18.5-24.9 kg/m²).

Conclusions:

• The impact of obesity on the overall dementia burden is likely underestimated in current literature.
• Accurate assessment of the obesity-dementia link requires careful consideration of the temporal relationship to avoid erroneous conclusions.