Relationship between peripheral neuropathy and cognitive performance in the elderly population

There are only a few studies that have shown an association of peripheral neuropathy with cognitive impairment in elderly individuals. Therefore, we investigated the relationship between cognitive performance and peripheral neuropathy. From the database of the National Health and Nutrition Examination Survey (NHANES, 1999–2002), each participant completed a household interview, physical performance test, questionnaire regarding personal health, and Digit Symbol Substitution Test (DSST) to evaluate cognitive performance. The severity of peripheral neuropathy was assessed based on the number of insensate areas in both feet during monofilament examination. We used the multivariate linear regression to analyze the association of the DSST findings with insensate areas of the worse foot. There were 828 participants in our study from NHANES 1999 to 2002; their mean age was 69.96 ± 7.38 years, and 51.3% were male. The β coefficients of the number of insensate areas associated with the DSST findings were all negative values, and the absolute value increased as the number of insensate areas increased. After adjustment for pertinent variables, the correlations remained significantly negative (all P for trend <.001). In addition, subgroup analysis showed no gender differences in the negative association, but this association was not significant in obese participants (P > .05). Our study provides evidence that the severity of peripheral neuropathy is significantly negatively correlated with cognitive performance.