Effect of serum uric acid to creatinine ratio on cognitive function decline in middle-aged adults: Longitudinal evidence from CHARLS

Background Serum uric acid (SUA) was a predictor of cognitive function. The association of SUA/serum creatinine ratio (Scr), which represents renal function-normalized SUA and cognitive function is unknown. Objective This study investigated the association of the SUA/Scr with cognitive function and the potential mediation effect of inflammation in the above relationship. Methods This study used 1–5 waves of data from the China Health and Retirement Longitudinal Study. 3302 participants aged 45–60 years at baseline were included. Among them, 1129 who attended subsequent 2–3 waves were further included for cumulative exposure calculation to the SUA/Scr ratio. The Cox models were used to evaluate the impact of baseline SUA/Scr ratio and its cumulative exposure on cognitive function decline. Results During a median follow-up of 8.6 years, there were 1512 (45.8%) cognitive function declined. After adjustment, the highest quartile of the SUA/SCr ratio was associated with the highest risk of cognitive function decline (Hazard ratio, 1.175; 95% confidence interval, 1.015–1.360). Restricted cubic spline showed a linear association between the SUA/Scr ratio and the risk of cognitive function decline (p non−linear = 0.514). There were a stronger association of cumulative SUA/Scr ratio and its exposure burden with cognitive function decline [the highest versus lowest quartile: 1.635 (1.006–2.656), the high versus low group: 1.729 (1.212–2.466), respectively]. No significant mediating effect through white blood cell count or C-reactive protein in SUA/Scr ratio-cognitive function decline was found. Conclusions The SUA/Scr ratio was associated with a higher risk of cognitive decline, whereas the mechanism mediated by inflammation indicators was not found.