Correlation between white matter alterations and cognitive function decline in early Alzheimer's disease

Abstract

Objective To investigate the effects of early stage Alzheimer's disease(AD)on white matter(WM)integrity using diffusion tensor imaging(DTI)and its relationship with cognitive function decline.Methods DTI was performed in 32 subjects,including 14 early AD patients and 18 elder controls(ON)with a 1.5 T MR scanner. Fractional anisotropy(FA)and mean diffusivity(-D)values were computed and compared for 9 regions of interest(ROI).Eight standard neuropsychological tests were performed and compared between AD and ON to evaluate basic cognitive capacities of AD.Correlation analysis was applied between FA,(-D) values and scores of neuropsychological tests for all subjects.Results FA significantly decreased in splenium of the corpus callosum and the posterior parietal-temporal region(S2),and D significantly increased in the splenium in AD patients(P＜0.05).AD patients showed lower scores compared with ON in all neuropsychological tests(P＜0.05).FA of the splenium and S2 positively correlated with several tests scores,while (-D) of multiple ROIs negatively correlated with several tests scores (P＜0.05).Conclusions In the early stage of AD,neuropathology has effect not only on cognitive function,but also on white matter structure,and they have strong relationship.AD patients show white matter changes in specific regions,which reflect loss in cortico-cortical connections. Key words: Alzheimer disease; Magnetic resonance imaging; Cognition disorders