Low lean mass and cognitive performance: data from the National Health and Nutrition Examination Surveys

Low lean mass and cognitive impairment are both age-related diseases. In addition, these conditions share many risk factors. However, the association between them has been controversial in recent years.

To investigate the association between low lean mass and cognitive performance in U.S. adults using NHANES data from 1999 to 2002.

A total of 2550 participants were identified in the National Health and Nutrition Examination Survey Database (1999-2002). The independent variable was low lean mass, and the dependent variable was cognitive performance. Men and women were classified as having low lean mass if appendicular lean mass (ALM) adjusted for BMI (ALM_BMI) was < 0.789 and < 0.512, respectively. Cognitive performance was assessed using the Digit Symbol Substitution Test (DSST). Higher scores on the DSST indicated better cognitive performance. The covariates included sex, age, race, poverty income ratio, comorbidity index, educational level, physical activity and smoking status.

For the primary outcome, our multivariate linear regression analysis indicated that participants without low lean mass were associated with better cognitive performance (β = 1.50; 95% CI [0.12-2.89]). Subgroup analysis results indicated that the association was similar in sex, age, race, poverty income ratio, comorbidity index, educational level, physical activity and smoking status.

Participants without low lean mass were associated with better cognitive performance. We might be able to improve cognitive performance by treating low lean mass, thus providing an opportunity for intervention at a younger age.