Among 45 adults who used both alcohol and cannabis, those with alcohol use disorder showed reduced occipital alpha brain wave responses during a visual task, regardless of whether they also had cannabis use disorder.
Neuroscience researchers, addiction specialists, and anyone interested in how different substances independently affect brain function.
AUD-related alpha blunting scaled with symptom severity, independent of cannabis
What the researchers found
Participants meeting criteria for alcohol use disorder displayed significantly blunted occipital alpha (8-16 Hz) responses during visual-spatial processing, and this effect scaled with AUD symptom severity. No independent effect of cannabis use disorder was observed on any neural oscillatory measure.
Why it matters
Most brain imaging studies of substance use examine one substance at a time, making it hard to tease apart overlapping effects. This study specifically separated the neural impacts of alcohol and cannabis addiction in people who used both.
The numbers in context
45 adults; 17 met criteria for AUD; 26 met criteria for CUD; all used both substances; alpha frequency range 8-16 Hz; blunted response scaled with AUD severity
How the study worked
Forty-five adults who used both alcohol and cannabis underwent structured clinical interviews (SCID-V) to determine AUD and/or CUD status, then completed a visual-spatial processing task during magnetoencephalography (MEG). A 2x2 ANCOVA identified independent effects of AUD and CUD on oscillatory brain activity.
What this study cannot tell us
Small sample of 45 participants. Cross-sectional design cannot determine whether AUD caused the neural changes or vice versa. Focused only on visual processing; other brain regions may show different patterns.
How to read the evidence
Small sample limits generalizability, though the 2x2 design effectively separating AUD and CUD effects and use of MEG provide methodological strength.
When this study was published
Published in 2021.
The bigger picture
By examining people who use both substances, this study provides clearer evidence that alcohol addiction specifically disrupts visual cortex oscillatory dynamics, while cannabis use disorder does not appear to independently affect these same neural processes.
Questions still open
- Do these alpha wave changes normalize with sustained abstinence from alcohol? Would larger studies reveal independent cannabis effects in other brain regions? Could alpha oscillatory measures serve as a biomarker for AUD severity?
Common questions
Did cannabis use disorder affect brain waves?
Why does this matter for understanding addiction?
Read the original research
Occipital neural dynamics in cannabis and alcohol use: independent effects of addiction.
Scientific reports, 11(1), 22258
Citation
Lew, Brandon J; Salimian, Anabel; Wilson, Tony W. (2021). Occipital neural dynamics in cannabis and alcohol use: independent effects of addiction.. Scientific reports, 11(1), 22258. https://doi.org/10.1038/s41598-021-01493-y
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