Racial Differences in Gray Matter Integrity by Diffusion Tensor in Black and White Octogenarians

Area of Science:

• Neuroscience
• Gerontology
• Radiology

Background:

• Racial disparities exist in cognitive aging and brain health.
• Understanding brain structural differences is crucial for targeted interventions.

Purpose of the Study:

• To quantify racial differences in brain structural characteristics in white and Black octogenarians.
• To examine the contribution of these characteristics to cognitive function.

Main Methods:

• Cross-sectional study of 283 adults (79-89 years old).
• Assessed gray matter integrity (mean diffusivity), gray matter atrophy, and white matter hyperintensities using diffusion tensor imaging.
• Analyzed cognitive performance using Digit Symbol Substitution Test (DSST) and Modified Mini-Mental State Examination (3MS), stratified by race.

Main Results:

• Black participants had lower DSST and 3MS scores but higher gray matter microstructural integrity (lower mean diffusivity) compared to whites, independent of several covariates.
• No significant racial differences were found for white matter hyperintensities or gray matter atrophy.
• Among Black individuals, mean diffusivity and white matter hyperintensities were associated with DSST scores.
• Among white individuals, mean diffusivity was significantly associated with both DSST and 3MS scores.

Conclusions:

• Black octogenarians demonstrated superior gray matter microstructural integrity compared to white individuals.
• This neuroimaging marker correlated with higher cognitive function, even with co-existing white matter hyperintensities and cardiovascular conditions.
• Microstructural gray matter integrity may represent a therapeutic target for enhancing cognition in aging populations, especially Black individuals with chronic cardiovascular conditions.