ACUTE WHITE MATTER INTEGRITY INCREASES AFTER A MODERATE DOSE OF ALCOHOL ADMINISTRATION

Abstract Background Chronic heavy alcohol consumption is known to harm health, while occasional light to moderate drinking may have potential benefits. However, it is unclear how modest alcohol intake affects brain structure. Aims & Objectives This study aimed to examine the white matter integrity changes after a modest dose of acute alcohol consumption using diffusion tensor imaging (DTI). Method Healthy individuals aged between 20 and 29, with ALDH2*1/*2 genotype, who understood the study and gave written informed consent were included in this study. They received an intravenous alcohol infusion using the alcohol clamp method to achieve a target blood alcohol concentration of 0.50 mg/mL. We acquired DTI data on a 3T MRI scanner at Kurihama Medical and Addiction Center and assessed self-reported clinical responses to alcohol administration (i.e., stimulus, physical, or sedative) using the visual analogue scale (VAS) at baseline (T0), 90 minutes after alcohol administration started (T1), and 90 minutes after alcohol administration ended (i.e., 180 minutes from baseline) (T2). We compared whole-brain fractional anisotropy (FA)/mean diffusivity (MD) values and FA/MD values for 48 regions of interest (ROI) extracted from the JHU-ICBM-DTI-81 white matter atlas across time using repeated-measure analysis of variance (ANOVA). Additional analyses were conducted to examine the correlation between baseline FA/MD value or FA/MD value changes and changes in behavioral VAS scores. Furthermore, we performed tract-based spatial statistics (TBSS) to compare white matter integrity between conditions (i.e., T0 vs T1, T0 vs T2, T1 vs T2). Results The study consisted of 18 participants, with an average age of 25.1 years, of which 7 (38.9%) were male. Repeated measures ANOVA showed no significant differences in the whole FA/MD or FA/MD values in any DTI ROIs among the three time points. TBSS analysis revealed no significant differences in FA/MD between T1 and T0 or T2 and T1. However, there were significant increases in FA in the cerebral white matter voxel cluster at T2 compared to T0 (37,145 voxels, p=0.001, FWE-corrected), whereas no significant decreases were found. Moreover, there were significant decreases in MD in the voxel clusters, including right anterior corona radiata, right inferior fronto-occipital fasciculus, corticospinal tract, left uncinate fasciculus, anterior thalamic radiation at T2 compared to T0 (>1000 voxels, p<0.05, FWE-corrected) whereas no significant increases were found. The whole FA change from T0 to T1 showed a negative correlation with the change in the sedative score from T0 to T1 (r=-0.51, p=0.03), which did not survive after the multiple comparison correction. No other significant correlations were found between whole FA/MD changes and behavioral score changes from T0 to T1 or T0 to T2. No correlation was shown between baseline FA/MD value and the FA/MD value changes or behavioral score changes from T0 to T1 or T0 to T2. Discussion & Conclusion This study indicates that a single, moderate alcohol consumption may increase the white matter integrity. However, the chronic effects of consistent moderate drinking on the brain's structure warrant further exploration.