Adults with childhood ADHD who used cannabis showed weaker thalamus-to-parietal brain connectivity compared to non-users, while non-users had stronger-than-normal connections in these regions.
People with ADHD considering cannabis use, neuroscience researchers
18 cannabis users vs 15 non-users studied
What the researchers found
Cannabis-using adults with childhood ADHD (n=18) had significantly decreased thalamic-parietal functional connectivity compared to non-users (n=15). Non-users showed increased thalamoparietal and thalamofrontal connectivity relative to a normative comparison group.
Why it matters
ADHD and substance use disorders share disrupted brain circuits. Understanding how cannabis interacts with ADHD-related brain connectivity could inform why people with ADHD use cannabis at higher rates.
The numbers in context
18 cannabis users vs 15 non-users with childhood ADHD; 7 normative comparisons; decreased connectivity in inferior parietal regions
How the study worked
Researchers analyzed resting-state fMRI data from the Addiction Connectome Preprocessed Initiative database, comparing thalamic connectivity maps between cannabis users and non-users with childhood ADHD diagnoses.
What this study cannot tell us
Very small sample size (33 total). Cross-sectional design cannot determine whether cannabis caused connectivity differences or whether pre-existing differences influenced cannabis use.
How to read the evidence
Very small cross-sectional neuroimaging study that cannot establish causation.
When this study was published
Published in 2022
The bigger picture
People with ADHD use cannabis at elevated rates, sometimes reporting self-medication for symptoms. This study suggests cannabis use may weaken brain connections that could otherwise compensate for ADHD-related deficits.
Questions still open
- Do the stronger thalamoparietal connections in non-users serve a protective function against cannabis use? Would longitudinal imaging clarify whether cannabis weakens these connections over time?
Common questions
What does weaker thalamic connectivity mean for ADHD?
Does this mean cannabis worsens ADHD?
Read the original research
Thalamocortical functional connectivity and cannabis use in men with childhood attention-deficit/hyperactivity disorder.
PloS one, 17(11), e0278162
Citation
Lee, Sanghyun; Hong, Soon-Beom. (2022). Thalamocortical functional connectivity and cannabis use in men with childhood attention-deficit/hyperactivity disorder.. PloS one, 17(11), e0278162. https://doi.org/10.1371/journal.pone.0278162
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