Effects of Aging on Frontal White Matter Microstructure in Alcohol Use Disorder and Associations With Processing Speed

Objective: The number of older adults with alcohol use disorder (AUD) is expected to significantly increase in the coming years. Both aging and AUD have been associated with compromised white matter microstructure, although the extent of combined AUD and aging effects is unclear. This study investigated interactions between aging and AUD in cerebral white matter integrity using diffusion tensor imaging (DTI). Method: All participants (44 recently detoxified participants with AUD and 28 healthy controls; ages 31-64 years) completed neurocognitive testing and a DTI scan. Regions of interests were identified on Tract-Based Spatial Statistics images. Hierarchical multiple regression was used to examine interactions between age and AUD status on DTI values [e.g., fractional anisotropy (FA)]. Results: Significant Age x AUD interactions were found across several prefrontal white matter regions (R-2 Delta = 5%-9%). Regional FA was negatively associated with age in the AUD group (rs = -.33-.53) but not in the control group (rs = .18-.32). This pattern remained after adjusting for lifetime history of drinking and recent drinking. Lifetime alcohol consumption negatively correlated with frontal white matter integrity in the AUD group (rs = -.33-.40). Finally, processing speed was significantly slower in the AUD group versus controls (p = .001) and was positively correlated with FA values in frontal white matter regions (rs = .34-.53). Conclusions: Cumulative alcohol consumption may affect frontal white matter integrity, and persons with AUD may be more prone to reductions in frontal white matter integrity with advancing age. These reductions in frontal white matter integrity may contribute to reductions in processing speed.