White matter characterization of adolescent binge drinking with and without co-occurring marijuana use: a 3-year investigation

Abstract

The aims of this study were to investigate the consequences of prolonged patterns of alcohol and marijuana use on white matter integrity and neurocognitive functioning in late adolescence, and examine neurodevelopmental trajectories over three years of regular follow-up visits. Three groups of demographically similar teens received assessments every 1.5 years (controls with consistently minimal substance use, n=16; teens who gradually increase their heavy episodic drinking n=17, and continuous binge drinkers with heavy marijuana use, n=21), including comprehensive neuropsychological evaluations, diffusion tensor imaging, and detailed substance use interviews. One-way ANOVA identified fifteen white matter clusters that significantly differed between groups at 3-year follow-up, ages 19-22; controls consistently demonstrated higher values of tissue integrity across fiber tracts. Repeated measures ANOVA revealed significant declines in white matter integrity from baseline to 3-year follow-up in the subsample of substance users, along with poorer global neurocognitive performance in alcohol users with heavy marijuana use by the 18-month follow-up. Findings suggest healthier brain white matter microstructure and better neurocognitive performance for teens free from heavy alcohol and marijuana use. Long-term engagement in these substances may adversely influence white matter and increase vulnerability for development of neuropathology purported to underlie future risk-taking and addictive behaviors.

Keywords: Adolescence; Alcohol; Brain; Cannabis; Cognition; Diffusion tensor imaging.

Figure 1

Timeline of study procedures and corresponding sample sizes for valid data at each time point.

Figure 2

Substance use characteristics, (N = 54) at baseline, 18-month follow-up (1.5 Years), and 3-year follow-up.

Figure 3

Selected regions demonstrating between group differences at year 3. Repeated measures ANOVA performed within user groups only at all three time points. Controls not included in repeated measures analysis, FA values from 3-year follow-up represented at each time point for controls and included in figure as reference point only. * p < 0.01, corrected, between group differences at 3-year follow-up

Figure 4

Observed global neuropsychological performance at baseline, 18-month follow-up and 3-year follow-up (Controls (CON), n = 15; Binge Drinkers (BG), n = 17; Binge Drinkers with Heavy Marijuana Use (BG+MJ), n = 19) * p < 0.01

Figure 5

White matter integrity in the right superior longitudinal fasciculus at three-year follow-up and change in global neuropsychological functioning from 18-month follow-up to three-year follow-up (N = 51; Controls (CON), n = 15; Binge Drinkers (BG), n = 17; Binge Drinkers with Heavy Marijuana Use (BG+MJ), n = 19)