Imagine trying to put together a jigsaw puzzle without seeing the picture on the box. That’s what scientists are doing as they try to understand how changes in our brain structure impact our cognitive abilities. In a recent study, researchers examined 995 individuals from a community-based population to investigate the link between white matter integrity, cortical structure, and cognitive impairments. They used various neurocognitive tests to assess cognitive status and acquired structural and diffusional MRI data to analyze brain structure. The results showed that disrupted white matter integrity and alterations in regional cortical surface area were associated with cognitive impairments, particularly in visuomotor processing speed, semantic memory, and executive function. Interestingly, the study also found that certain areas of the cortex were independently related to cognitive scores, regardless of their connection to white matter tracts. These findings shed light on the complex relationship between brain structure and cognition in community-dwelling populations. To dive deeper into this fascinating research, check out the full article!

ObjectiveFurther studies are needed to improve the understanding of the pathological process underlying cognitive impairments. The purpose of this study is to investigate the global and topographic changes of white matter integrity and cortical structure related to cognitive impairments in a community-based population.MethodsA cross-sectional analysis was performed based on 995 subjects (aged 56.8 ± 9.1 years, 34.8% males) from the Shunyi study, a community-dwelling cohort. Cognitive status was accessed by a series of neurocognitive tests including Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), category Verbal Fluency Test (VFT), Digit Span Test (DST), and Trail Making Tests A and B (TMT-A and TMT-B). Structural and diffusional MRI data were acquired. White matter integrity was assessed using fractional anisotropy (FA), mean diffusivity (MD), and peak width of skeletonized mean diffusivity (PSMD). Cortical surface area, thickness, and volume were measured using Freesurfer. Probabilistic tractography was further conducted to track the white matter fibers connecting to the cortical regions related to cognition. General linear models were used to investigate the association between brain structure and cognition.ResultsGlobal mean FA and MD were significantly associated with performances in VFT (FA, β 0.119, p < 0.001; MD, β −0.128, p < 0.001). Global cortical surface area, thickness, and volume were not related to cognitive scores. In tract-based spatial statistics analysis, disruptive white matter integrity was related to cognition impairment, mainly in visuomotor processing speed, semantic memory, and executive function (TMT-A and VFT), rather than verbal short-term memory and working memory (DST). In the whole brain vertex-wise analysis, surface area in the left orbitofrontal cortex, right posterior-dorsal part of the cingulate gyrus, and left central sulcus were positively associated with MMSE and MoCA scores, and the association were independent of the connecting white matter tract.ConclusionDisrupted white matter integrity and regional cortical surface area were related to cognition in community-dwelling populations. The associations of cortical surface area and cognition were independent of the connecting white matter tract.

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