Correlation between sarcopenia index and cognitive function in older adult women: A cross-sectional study using NHANES data

Objectives The Sarcopenia Index (SI) has the potential as a biomarker for sarcopenia, which is characterized by muscle loss. There is a clear association between sarcopenia and cognitive impairment. However, the relationship between SI and cognitive impairment is yet to be fully understood. Methods We employed data extracted from the U.S. National Health and Nutrition Examination Survey (NHANES) spanning the years 1999 to 2002. Our study encompassed individuals aged 65 to 80 who possessed accessible information regarding both SI and cognitive evaluations with a GFR ≥ 90. Cognitive function was assessed using the digit symbol substitution test (DSST). SI was calculated by serum creatinine (mg/dL)/cystatin C (mg/L)*100. Employing multivariate modeling, we estimated the connection between SI and cognitive performance. Furthermore, to enhance the reliability of our data analysis, we categorized SI using tertiles and subsequently calculated the P-value for trend. Results After adjustment for potential confounders, we found SI was significantly and positively correlated with cognitive function scores both in older female in the American population [β = 0.160, 95 % confidence interval (CI) 0.050 to 0.271, P = 0.00461]. Similarly, when the total cognitive function score was treated as a categorical variable according to tertiles, higher SI was related to better total cognitive function scores in females [odds ratio (OR) = 3.968, 95 % CI 1.863 to 6.073, P = 0.00025] following adjustment for confounders. Conclusions Higher SI was correlated with a lower prevalence of cognitive impairment among older adult women with normal kidney function.