Bone mineral density and verbal memory impairment - Third National Health and Nutrition Examination Survey

Previous studies have examined the relation of endogenous estrogen levels o r estrogen replacement therapy to the risk of poor cognitive function, but results have been inconclusive. Bone mineral density has been proposed as a marker for cumulative estrogen exposure. The authors studied the relation of bone mineral density to the prevalence of verbal memory impairment among 4,304 elderly subjects in the Third National Health and Nutrition Examinat ion Survey (1988-1994). Bone mineral density was measured in five regions o f the proximal femur with dual-energy x-ray absorptiometry. Verbal memory w as assessed using delayed recall of a three-item word list and a six-item s tory. Verbal memory impairment was defined as a combined score of <4. The p revalence of verbal memory impairment for each increasing bone mineral dens ity quintile at the femoral neck was 8.35, 5.74, 5.22, 5.00, and 3.38% in w omen and 11.54, 7.27, 8.47, 6.29, and 5.89% in men, respectively. With adju stment for age, sex, and other covariates, the prevalence ratios of verbal memory impairment for each increased bone mineral density quintile were 1.0 0, 0.64, 0.65, 0.55, and 0.44, respectively (p for trend < 0.001). These re sults suggest that bone mineral density in the elderly is associated with v erbal memory impairment. The mechanisms underlying this relation are not un derstood, but cumulative exposure to estrogen may play a role.