Associations between white matter structural properties and global cognition as measured by MoCA scores in older adults

Background / Objective The Montreal Cognitive Assessment (MoCA) is a widely used tool for evaluating global cognitive function across multiple domains, including memory, attention, language, visuospatial skills, and executive function. White matter (WM) in the brain, composed of myelinated nerve fibers, is crucial for facilitating communication between different brain regions. Understanding the relationship between the structural integrity of WM and cognitive performance is essential for identifying biomarkers for cognitive decline and neurodegenerative diseases. This study aims to investigate the associations between the structural properties of white matter and global cognitive function as measured by MoCA scores in older adults with mild cognitive impairment (MCI). Methods Participants included 59 apparently healthy older adults (34 females and 25 males) aged 60–85 years. All underwent whole-brain structural 3T MRI (T1W, T2W, DTI). DTI images were checked for artifacts by an experienced neuroradiologist. Tractography was performed using the Siemens “syngo.via” workstation (Siemens Healthineers, Erlangen, Germany). Circular voxels (1 cm radius) were manually placed on regions of interest, and the software automatically calculated the median values of fractional anisotrophy (FA) and the number of tracts (NOT). For anatomical reference, a high-resolution T1W 3D structural image was acquired for all participants. Cognitive assessments were conducted by a qualified mental health care specialist, utilizing the MoCA test. Results Significant positive correlations were found between MoCA scores and the number of fiber tracts in the left and right temporal tapetum (NOT 21 and NOT 22: r-values ≥ 0.432, uncorrected p < 0.001). Other correlations did not reach significance (all uncorrected p-values ≥ 0.003), though trends with moderate effect sizes were observed between MoCA scores and the whole-brain number of fiber tracts (NOT 1: r = 0.375, uncorrected p = 0.005), FA of the left external capsule fiber tracts (FA 6: r = 0.361, uncorrected p = 0.007), and FA of the left temporal tapetum fiber tracts (FA 22: r = 0.342, uncorrected p = 0.011). No significant associations were found when HC and MCI groups were analyzed separately (all uncorrected p > 0.001). Conclusions Our study confirms associations between WM structural properties and MoCA scores. Higher FA values in specific WM tracts, particularly from the hippocampus and cingulate cortex, correlate positively with cognitive function, while reduced FA values in regions like the right sensorimotor cortex are linked to cognitive decline. These findings suggest that FA values and the number of tracts (NOT) in key WM regions can serve as reliable markers for monitoring cognitive decline and disease progression in MCI.