C‐reactive protein (CRP) blood concentrations associate with reduced global system segregation in middle‐aged individuals

Abstract

AbstractBackgroundHigh concentrations of circulating C‐reactive protein (CRP) have been related to poorer cognition in adults (Lewis et al. Age Ageing. 2021;50:2199). Within the Lifebrain consortium (Walhovd et al. Eur Psychiatry. 2018;50:47), we recently reported overall lifespan associations between increased CRP and smaller hippocampal (HPC) volumes, albeit these could not be observed in one subsample of middle‐aged individuals (Wang et al. Brain Behav Immun. 2022;100:243). Here we hypothesized that functional brain integrity measures would be sensitive to predict CRP levels in this group. We focused on global system segregation (SyS) a graph theory‐based metric which quantifies the extent to which major functional networks are segregated from each other.MethodWe included 336 volunteers (mean age 53.8; SD: 7.1; 47.9% women) from the Barcelona Brain Health Initiative (Cattaneo et al. Front Aging Neurosci. 2018;10:321). High‐sensitive CRP (hsCRP) concentrations were determined through dry blood samples and log10 transformed (Wang et al. Brain Behav Immun. 2022;100:243). Adjusted HPC volumes were estimated from T1‐wheigthed 3T MRI acquisitions (Raz et al. Cereb Cortex 2005;15:1676). SyS values were calculated (Ewers et al. Brain. 2021;144:2176) from 100 nodes defined by the Schaefer‐Yeo atlas (Fig 1a). Multiple linear regression investigated the associations between age, gender, cognitive function (MMSE and episodic memory), HPC volumes, APOE status and SyS as predictor variables and hs‐CRP as the dependent measure.ResultIn the adjusted model only SyS (β= ‐0.56, p<0.05) and APOE (β= ‐0.21, p=0.003) predicted hsCRP concentrations. Global SyS was negatively related to hsCRP (Fig 1b). As in Wang et al (2022), APOE E4 carriers (N=71; mean:‐0.43; SD=0.62) exhibited lower CRP circulating levels than non‐E4 bearers (N=265; mean: ‐0.20; SD=0.51; t=3.23, p<0.001), however there were no differences in SyS according to APOE genotypes (t=0.95, p=0.34).Conclusionhs‐CRP blood concentrations were predicted by global segregation of functional networks in absence of HPC volume or cognitive status effects. As such, blood derived hsCRP levels may represent an early indicator of middle‐age individual variations in a measure recently reported to predict future cognitive decline (Chan et al. Nat Aging 2021;1:1053) and represent a cognitive resilience mechanism in the face of AD pathology (Ewers et al. Brain. 2021;144:2176).