Segregation of brain systems is associated with cognitive and eye movement performance in the general population

Abstract

AbstractBackgroundThe human brain is a large‐scale network, which contains multiple segregated and functionally specialized systems. The organization of brain systems has been reported to change in a dedifferentiated way with increasing age. We investigated how age and sex are associated with brain system segregation during resting‐state in a large population‐based sample. Further, we analysed whether interindividual differences in the amount of brain system segregation are associated with cognitive and eye movement performance.MethodThe analyses were based on 3,256 participants (30‐95 years) of the Rhineland Study, a community‐based cohort study in Bonn, Germany. Functional connectivity (FC) was extracted from 200 ROIs within 7 systems (control, default, visual, somatomotor, dorsal attention, ventral attention and limbic) using resting‐state functional MRI acquired from 3T Siemens MAGNETOM Prisma MRI scanners. Segregation index was calculated using a previously established measurement taking the difference between mean within‐system FC and mean between‐system FC as a portion of mean within‐system FC. We assessed cognitive performance with tests for memory, processing speed, executive function and crystallized intelligence and an eye movement test battery. We used multivariable regression models to assess the relation between brain segregation index and cognitive and eye movement performance with adjustment for possible confounders.ResultThe global system segregation index decreased by 0.17 standard deviations (sd) per 10 years increase in age (95% confidence interval (CI): ‐0.19 – ‐0.14). Men had on average a 0.08 sd higher global system segregation index than women (95% CI: 0.02 – 0.15). Higher global system segregation was associated with higher performance in global cognition, processing speed, executive function, working memory and episodic verbal memory, and with lower crystallized intelligence. Additionally, higher global system segregation was associated with faster initiation of prosaccades and antisaccades.ConclusionHigher system segregation is beneficial for cognitive and eye movement tasks that place demands on processing speed, executive function and working memory, but crystallized intelligence is better when segregation is lower.