Relationships of inflammation trajectories with white matter volume and integrity in midlife

Abstract

OBJECTIVE\nElevated inflammation is associated with worse late-life cognitive functioning and brain health. Our goal was to examine the relationship between inflammation trajectories and white matter integrity in midlife.\n\n\nMETHODS\nParticipants were 508 adults from the Coronary Artery Risk Development in Young Adults Study (CARDIA; 51% female). Latent class analysis was used to identify inflammation trajectories based on repeated measures of the inflammatory marker C-reactive protein (CRP) over the 18 years before brain magnetic resonance imaging (MRI). Outcomes were brain MRI measures of total and region-specific white matter volume and integrity at a mean age of 50.6±3.4 years. Linear regression was used to examine if inflammation trajectories were associated with brain MRI outcomes, adjusting for potential confounds in all models and for disease and health behaviors in follow-up models.\n\n\nRESULTS\nLower-stable (38%), moderate-increasing (7%), and consistently-higher (54%), trajectories emerged. Compared to the lower-stable group, the moderate-increasing group showed lower white matter volume (β = -0.18, 95% CI -0.29, -0.06) and worse white matter integrity as indexed by lower fractional anisotropy (FA; β = -0.37, 95% CI -0.70, -0.04) and higher mean diffusivity (β = 0.44, 95% CI 0.11, 0.78) in the whole brain. The consistently-higher group showed lower whole-brain FA (β = -0.20, -0.38, -0.03). In exploratory analyses, the moderate-increasing group showed lower white matter volume, lower FA and higher MD in the frontal, temporal, and parietal lobes compared to the lower-stable group. The consistently-higher group showed lower white matter volume in the parietal lobe and lower FA in the frontal, temporal, and parietal lobes, but similar MD, compared to the lower-stable group. Findings for the moderate-increasing, but not the consistently-higher, group were robust to adjustment for disease and lifestyle factors.\n\n\nCONCLUSION\nIncreasing or high inflammation trajectories from early to mid adulthood are associated with worse brain health, as indexed by lower white matter volume and/or worse white matter integrity.