Knee height and arm span: A reflection of early life environment and risk of dementia

OBJECTIVES: To determine if anthropometric measures, as markers of early life environment, are associated with risk of dementia, Alzheimer disease (AD), and vascular dementia (VaD). METHODS: A total of 2,798 subjects were followed as part of the Cardiovascular Health Cognition Study for an average of 5.4 years; 480 developed dementia. Knee height was measured 3 years prior to and arm span 4 years after the study's baseline. Cox proportional hazard models were used to examine their association with subsequent risk of dementia, AD, and VaD. RESULTS: Among women, greater knee height and arm span were associated with lower risks of dementia (knee height: HR per 1-inch increase 0.84; 95% CI 0.74-0.96; arm span: HR per 1-inch increase 0.93; 95% CI 0.88-0.98) and AD (knee height: HR per 1-inch increase 0.78; 95% CI 0.65-0.93; arm span: HR per 1-inch increase 0.90; 95% CI 0.85-0.96). Women in the lowest quartile of arm span had ∼1.5 times greater risk of dementia (HR 1.45; 95% CI 1.03-2.05) and AD (HR 1.70; 95% CI 1.10-2.62) than other women. Among men, only arm span was associated with lower risks of dementia (HR per 1-inch increase 0.94; 95% CI 0.89-1.00) and AD (HR per 1-inch increase 0.92; 95% CI 0.84-1.00). For each gender, knee height was not associated with VaD, while arm span was associated with a nonsignificant lower risk of VaD. CONCLUSIONS: Our findings with knee height and arm span are consistent with previous reports and suggest early life environment may play an important role in the determination of future dementia risk.