Multivariate white matter microstructure alterations in older adults with coronary artery disease

Patients with coronary artery disease (CAD) face an increased risk of cognitive impairment, dementia, and stroke. While white matter (WM) lesions are frequently reported in patients with CAD, the effects on WM microstructure alterations remain largely unknown. We aimed to identify WM microstructural alterations in individuals with CAD compared to healthy controls (HC), and to examine their relationships with cognitive performance. Forty-three (43) patients with CAD and 36 HC aged 50 and older underwent comprehensive neuropsychological testing and multi-modal 3T MRI. A novel multivariate approach - the Mahalanobis distance (D2) - was used to quantify WM abnormalities as the amount of deviation from the HC reference group. D2 integrates multiple MRI-derived diffusion-weighted imaging, R1 relaxometry, and magnetization transfer imaging metrics, while accounting for covariance between metrics. Relationships between WM D2 and cognition (executive function and processing speed) were also assessed. Compared to HCs, patients with CAD had higher D2 values in the whole WM (p=0.009) and in the territories right anterior, bilateral middle, and right posterior cerebral artery territories (p<0.05). Myelin-sensitive metrics, particularly R1 relaxation rate and MT saturation (MTsat), were the most important contributors to D2. Processing speed was positively associated with greater R1 in both the whole WM and left middle cerebral artery territory. These findings suggest that greater WM microstructural alterations observed in patients with CAD were mainly driven by differences in myelin content, as R1 and MTsat were the most important contributors. These alterations may contribute to a heightened risk of cognitive impairment.