White Matter Microstructural Integrity Is Associated with Executive Function and Processing Speed in Older Adults...

Coronary artery disease (CAD) is associated with an increased risk of cognitive decline. Although cerebral white matter (WM) damage predicts cognitive function in CAD, conventional neuroimaging measures only partially explain the effect of CAD on cognition. The purpose of this study was to determine if WM microstructural integrity and CAD using diffusion tensor imaging (DTI) correlates with cognitive function in older adults with CAD.

Forty-nine CAD patients (66 ± 7 years old, 86% male) underwent neurocognitive assessments using the cognitive battery recommended by the National Institute of Neurological Disorders and Stroke-Canadian Stroke Network for the study of vascular cognitive impairment. Composite scores for each cognitive domain were calculated. Microstructural integrity in normal-appearing WM was quantified as fractional anisotropy (FA) using DTI in nine bilateral and two interhemispheric WM tracts from the Johns Hopkins University WM Tractography Atlas. Linear regression models examined associations between FA and cognitive performance, controlling for age, sex, and education, with correction for multiple comparisons using a false discovery rate of 5%.

Executive function was most significantly associated with FA in the left parahippocampal cingulum (β = 0.471, t = 3.381, df = 44, p = 0.002) and left inferior fronto-occipital fasciculus (β = 0.430, t = 2.984, df = 44, p = 0.005). FA was not associated with memory in any of the WM tracts examined.

These results suggest that WM microstructural integrity may be an important neural correlate of executive function even in cognitively intact CAD patients. This study suggests WM damage may be relevant to subtle cognitive decline in a population that may have early neural risk for dementia.