Association of the Irregular 3-Dimensional Shape of White Matter Hyperintensities with Cognitive Function

Abstract

Introduction: The irregular shapes of white matter hyperintensities (WMHs) are associated with poor cognitive function, diabetes, or lacunes. However, the association between the WMH shape and dementia remains understudied. We investigated the association between the calculated shape index of WMH and the diagnosis of dementia and cognitive function. Methods: The inverse sphericity index (ISIWMH) and volume of WMHs (VOLWMH) were compared among 82 participants with normal cognition, 82 with Alzheimer's dementia (AD), and 82 with subcortical vascular dementia (SVD). We examined the associations of ISIWMH and VOLWMH with the modified Hachinski Ischemic Score (mHIS), diagnosis of AD and SVD, and cognitive test scores, using linear, multinomial, or hierarchical linear regression models. Results: The mHIS was associated with both ISIWMH (β = 0.326, p < 0.001) and VOLWMH (β = 0.299, p < 0.001). Both ISIWMH and VOLWMH were associated with the SVD diagnosis (odds ratio [OR] = 2.685, p = 0.002, ISIWMH; OR = 2.597, p = 0.005, VOLWMH), but not with AD. The SVD diagnosis was better explained when the multinomial regression model included both ISIWMH and VOLWMH instead of VOLWMH alone (χ2 = 20.768, df = 2, p < 0.001). The Trail Making Test-D (TMT-D) scores of the SVD patients were associated with both ISIWMH (β = 0.308) and VOLWMH (β = 0.293). Conclusion: An irregular WMH shape may be associated with the high cerebrovascular component of cognitive impairment and the diagnosis and low cognitive flexibility of SVD, which may improve the prediction of SVD diagnosis when used in combination with WMH volume.