Alcohol and Cannabis Together Shrank Brain Gray Matter Faster Than Either Alone
Adolescents who used both alcohol and cannabis showed faster gray matter decline in five brain regions compared to those using either substance alone, with early onset amplifying the effect.
Quick Facts
What This Study Found
Co-use of alcohol and cannabis predicted faster gray matter volume decline (-0.046 to -0.138 cm3/year) in the caudal middle frontal cortex, fusiform, inferior frontal, superior temporal, and supramarginal gyri. These effects were not seen with alcohol or cannabis use alone and were more pronounced with early adolescent onset.
Key Numbers
724 adolescents; 370 female; decline rate -0.046 to -0.138 cm3/year; 5 affected brain regions; Bonferroni-corrected results
How They Did This
Longitudinal analysis of 724 adolescents (370 female) from the NCANDA study using mixed-effects modeling of brain MRI data across 34 regions of interest, with Bonferroni correction for multiple comparisons.
Why This Research Matters
Most brain imaging studies focus on one substance at a time. This study reveals that the combination of alcohol and cannabis poses a greater threat to adolescent brain development than either substance alone.
The Bigger Picture
Adolescents who use substances rarely stick to just one. This study suggests that polysubstance effects on the developing brain may be worse than the sum of individual substance effects.
What This Study Doesn't Tell Us
Cannot fully rule out pre-existing brain differences that led to substance use. Co-users were not using more alcohol than alcohol-only users, but other confounders may exist.
Questions This Raises
- ?Are these gray matter changes reversible with abstinence?
- ?Does the order of substance initiation (alcohol first vs cannabis first) matter for brain outcomes?
Trust & Context
- Key Stat:
- Co-use effects not seen with either substance alone
- Evidence Grade:
- Longitudinal design with a large well-characterized sample, repeated brain imaging, and Bonferroni correction for multiple comparisons.
- Study Age:
- Published in 2022
- Original Title:
- Alcohol and cannabis co-use and longitudinal gray matter volumetric changes in early and late adolescence.
- Published In:
- Addiction biology, 27(5), e13208 (2022)
- Authors:
- Luo, Xi, Yang, James J(2), Buu, Anne(3), Trucco, Elisa M, Li, Chiang-Shan R
- Database ID:
- RTHC-04022
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Is using alcohol and cannabis together worse for the teen brain?
This study found that co-use of alcohol and cannabis accelerated gray matter decline in five brain regions at rates not seen with either substance alone, suggesting the combination is uniquely harmful.
Does the age of first use matter?
Yes. Early adolescent onset of co-use predicted faster brain volume decline compared to later onset, particularly in the superior temporal and supramarginal gyri.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-04022APA
Luo, Xi; Yang, James J; Buu, Anne; Trucco, Elisa M; Li, Chiang-Shan R. (2022). Alcohol and cannabis co-use and longitudinal gray matter volumetric changes in early and late adolescence.. Addiction biology, 27(5), e13208. https://doi.org/10.1111/adb.13208
MLA
Luo, Xi, et al. "Alcohol and cannabis co-use and longitudinal gray matter volumetric changes in early and late adolescence.." Addiction biology, 2022. https://doi.org/10.1111/adb.13208
RethinkTHC
RethinkTHC Research Database. "Alcohol and cannabis co-use and longitudinal gray matter vol..." RTHC-04022. Retrieved from https://rethinkthc.com/research/luo-2022-alcohol-and-cannabis-couse
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.