High-sensitivity C-reactive protein and cognitive decline: the English Longitudinal Study of Ageing

Background. High-sensitivity C-reactive protein (hs-CRP) has been suggested to be involved in the process of cognitive decline. However, the results from previous studies exploring the relationship between hs-CRP concentration and cognitive decline are inconsistent. Method. We employed data from wave 2 (2004-2005) to wave 7 (2014-2015) of the English Longitudinal Study of Ageing. Cognitive function was assessed at baseline (wave 2) and reassessed biennially at waves 3-7. Results. A total of 5257 participants (54.9% women, mean age 65.4 +/- 9.4 years) with baseline hs-CRP levels ranged from 0.2 to 210.0 mg/L (median: 2.0 mg/L, interquartile range: 0.94.1 mg/L) were studied. The mean follow-up duration was 8.1 +/- 2.8 years, and the mean number of cognitive assessment was 4.9 +/- 1.5. Linear mixed models show that a one-unit increment in natural log-transformed hs-CRP was associated with faster declines in global cognitive scores [-0.048 points/year, 95% confidence interval (CI) -0.072 to -0.023], memory scores (-0.022 points/year, 95% CI -0.031 to -0.013), and executive function scores (-0.025 points/year, 95% CI -0.043 to -0.006), after multivariable adjustment. Compared with the lowest quartile of hs-CRP, the multivariable-adjusted rate of global cognitive decline associated with the second, third, and highest quartile was faster by -0.043 points/year (95% CI -0.116 to 0.029), -0.090 points/year (95% CI -0.166 to -0.015), -0.145 (95% CI -0.221 to -0.069), respectively (p for trend <0.001). Similarly, memory and executive function also declined faster with increasing quartiles of hs-CRP. Conclusions. A significant association between hs-CRP concentration and long-term cognitive decline was observed in this study. Hs-CRP might serve as a biomarker for cognitive decline.