gray matter- luo et al (2022)

Background & Purpose

  • Adolescence is a critical period for brain development, especially in cortical regions linked to executive control, decision-making, and social behavior.

  • Both alcohol and cannabis are widely used by adolescents, often together.

  • This study aimed to determine how alcohol alone, cannabis alone, and alcohol + cannabis co-use affect gray matter volume (GMV) trajectories.

Methods

  • Longitudinal neuroimaging study.

  • Participants: adolescents tracked from early to middle adolescence.

  • MRI scans measured GMV over time.

  • Groups: alcohol-only users, cannabis-only users, co-users, and non-users.

Findings

  • Alcohol + cannabis co-use → significantly faster GMV decline compared to non-users and single-substance users.

  • Affected regions included:

    • Frontal cortex → executive function, decision-making, inhibitory control.

    • Superior temporal gyrus → auditory processing, language, and social cognition.

    • Supramarginal gyrus → empathy, emotional regulation.

    • Fusiform gyrus → facial recognition, social processing.

  • Alcohol-only users: also showed decline, but less severe than co-use group.

  • Cannabis-only users: less pronounced changes, suggesting alcohol was the stronger driver, though synergy made co-use most harmful.

Implications

  • Alcohol accelerates cortical thinning during a vulnerable period of brain development.

  • Co-use with cannabis worsens structural decline, possibly due to overlapping effects on neuronal plasticity.

  • Early structural damage may increase vulnerability to substance dependence and psychiatric issues later in life.

  • Suggests prevention strategies should focus especially on adolescents who co-use alcohol and cannabis.