Reward-Related Brain Activity Prospectively Predicts Increases in Alcohol Use in Adolescents

Abstract

Objective: Altered activity within reward-related neural regions, including the ventral striatum (VS) and medial prefrontal cortex (mPFC), is associated with concurrent problematic substance use. The aims of the present study were (a) to identify patterns of reward-related neural activity that prospectively predicted changes in alcohol use 2 years after magnetic resonance imaging in a sample of adolescents, and (b) to examine whether these patterns differed by sex. We also tested whether depression symptoms or impulsivity mediated associations between neural activity and future alcohol use.

Method: Participants were 262 adolescents (129 male and 133 female) of Mexican origin who completed the Monetary Incentive Delay task during a functional magnetic resonance imaging scan at age 16. Participants reported on their alcohol use at ages 16 and 18.

Results: Results indicated that different patterns of reward-related neural activity predicted future increases in alcohol use for male and female adolescents. In boys, higher VS activity during reward anticipation and average ventral mPFC activity during reward feedback predicted increases in alcohol use from age 16 to 18 years; in girls, higher dorsal mPFC activity and blunted VS activity during reward anticipation predicted increases in alcohol use from age 16 to 18 years. Depression symptoms or impulsivity did not mediate these associations.

Conclusion: The results suggest that different pathways of risk may lead to problematic alcohol use for adolescent boys and girls. These sex differences in neural risk pathways have important implications for prevention and intervention approaches targeting Mexican-origin youth.

Keywords: adolescence; alcohol; fMRI; reward; sex.

Figure 1.. Main Effects of the Task

Note: A. Bilateral ventral striatum (VS) and dorsal medial prefrontal cortex (mPFC) activity for the contrast of gain cues > neutral cues, minimum threshold t = 2.575, p<.05 corrected for each search region. B. Bilateral VS and ventral mPFC activity for the contrast of gain feedback > neutral feedback, minimum threshold t = 2.575, p<.05 corrected for each search region.

Figure 2.. Association Between Dorsal Medial Prefrontal Cortex (dmPFC) Activation to Gain Cues > Neutral Cues and Future Alcohol Use in Male and Female Adolescents

Note: Lines are plotted for dorsal mPFC activity (mean-centered) from 1.5 standard deviations below the mean to 1.5 standard deviations above the mean using coefficients from the Poisson model (see Table S2, available online). Points on the y-axis represent age 18 alcohol use (see methods for description of how alcohol use was calculated).

Figure 3.. Association Between Bilateral Ventral Striatum (VS) Activation to Gain Cues > Neutral Cues and Future Alcohol Use in Male and Female Adolescents

Note: Lines are plotted for VS activity (mean-centered) from 1.5 standard deviations below the mean to 1.5 standard deviations above the mean using coefficients from the Poisson model (see Table S2, available online). Points on the y-axis represent age 18 alcohol use.

Figure 4.. Association Between Ventral Medial Prefrontal Cortex (vmPFC) Activation to Gain Feedback > Neutral Feedback and Future Alcohol Use in Male and Female Adolescents

Note: Lines are plotted for ventral mPFC activity (mean-centered) from 1.5 standard deviations below the mean to 1.5 standard deviations above the mean using coefficients from the Poisson model (see Table S3, available online). Points on the y-axis represent age 18 alcohol use.