ADHD Reduced Brain Activity for Impulse Control Regardless of Cannabis Use
Young adults with childhood ADHD showed impaired impulse control and reduced brain activation independent of cannabis use, though cannabis users without ADHD recruited compensatory brain regions.
Quick Facts
What This Study Found
Researchers compared brain function during an impulse control task (Go/NoGo) across four groups: ADHD with and without cannabis use, and controls with and without cannabis use.
Participants with ADHD made significantly more errors on the task and showed less activation in frontal and parietal brain regions and frontal-striatal circuits, regardless of whether they used cannabis. Cannabis use alone did not significantly affect task performance or brain activation.
However, an interaction emerged: control participants who used cannabis showed increased activation in the hippocampus and cerebellar vermis (areas rich in cannabinoid receptors) during successful impulse control. ADHD participants who used cannabis did not show this pattern. The researchers suggest controls may have recruited these regions as compensatory circuits, while ADHD participants could not.
Key Numbers
73 participants across 4 groups. ADHD participants made more commission errors. ADHD showed less frontoparietal/frontostriatal activation. Cannabis-using controls showed increased hippocampal and cerebellar activation. Cannabis-using ADHD participants did not show compensatory recruitment.
How They Did This
Cross-sectional fMRI study comparing four groups: childhood ADHD with monthly cannabis use (n=25), childhood ADHD without cannabis use (n=25), local normative controls with cannabis use (n=11), and controls without cannabis use (n=12). Participants completed a Go/NoGo task during functional MRI scanning. Behavioral performance and brain activation patterns were analyzed for main effects and interactions.
Why This Research Matters
This study helps disentangle the often-conflated effects of ADHD and cannabis on the brain. The finding that ADHD dominates the brain activation pattern regardless of cannabis use, while cannabis elicits compensatory activity only in non-ADHD brains, suggests that ADHD and cannabis use interact differently with impulse control circuitry than either condition alone would predict.
The Bigger Picture
People with ADHD are at elevated risk for substance use, and cannabis is among the most commonly used substances. Understanding that ADHD-related brain differences persist regardless of cannabis use, and that the brain's compensatory response to cannabis may be impaired in ADHD, is important for understanding vulnerability to cannabis-related impairment in this population.
What This Study Doesn't Tell Us
Small group sizes, particularly the control groups (11 and 12 participants). Cross-sectional design prevents causal conclusions. Cannabis use was defined as monthly or more, which includes a wide range of use patterns. The study focused on childhood ADHD, so results may not apply to adult-onset attention difficulties.
Questions This Raises
- ?Why can't ADHD brains recruit compensatory circuits in response to cannabis?
- ?Does this failure of compensation contribute to greater cannabis-related impairment in people with ADHD?
- ?Would heavier cannabis use overwhelm the compensatory mechanism seen in controls?
Trust & Context
- Key Stat:
- ADHD reduced frontoparietal brain activation for impulse control regardless of cannabis use.
- Evidence Grade:
- Moderate evidence from a controlled neuroimaging study, though small group sizes (especially controls) limit statistical power and generalizability.
- Study Age:
- Published in 2016. Neuroimaging of ADHD-cannabis interactions continues to be an active research area.
- Original Title:
- ADHD and cannabis use in young adults examined using fMRI of a Go/NoGo task.
- Published In:
- Brain imaging and behavior, 10(3), 761-71 (2016)
- Authors:
- Rasmussen, Jerod, Casey, B J, van Erp, Theo G M, Tamm, Leanne, Epstein, Jeffery N, Buss, Claudia, Bjork, James M, Molina, Brooke S G, Velanova, Katerina, Mathalon, Daniel H, Somerville, Leah, Swanson, James M, Wigal, Tim, Arnold, L Eugene, Potkin, Steven G
- Database ID:
- RTHC-01247
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Does cannabis make ADHD worse?
This study found that ADHD impaired impulse control and brain activation independently of cannabis use. Cannabis did not appear to make ADHD-related brain function worse, but unlike in non-ADHD brains, ADHD brains could not recruit compensatory regions in response to cannabis.
Can the brain compensate for cannabis effects?
In people without ADHD, the brain appeared to recruit additional regions (hippocampus and cerebellum) during impulse control after cannabis use, possibly as a compensatory mechanism. This did not happen in people with ADHD, suggesting ADHD may limit the brain's ability to compensate.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-01247APA
Rasmussen, Jerod; Casey, B J; van Erp, Theo G M; Tamm, Leanne; Epstein, Jeffery N; Buss, Claudia; Bjork, James M; Molina, Brooke S G; Velanova, Katerina; Mathalon, Daniel H; Somerville, Leah; Swanson, James M; Wigal, Tim; Arnold, L Eugene; Potkin, Steven G. (2016). ADHD and cannabis use in young adults examined using fMRI of a Go/NoGo task.. Brain imaging and behavior, 10(3), 761-71. https://doi.org/10.1007/s11682-015-9438-9
MLA
Rasmussen, Jerod, et al. "ADHD and cannabis use in young adults examined using fMRI of a Go/NoGo task.." Brain imaging and behavior, 2016. https://doi.org/10.1007/s11682-015-9438-9
RethinkTHC
RethinkTHC Research Database. "ADHD and cannabis use in young adults examined using fMRI of..." RTHC-01247. Retrieved from https://rethinkthc.com/research/rasmussen-2016-adhd-and-cannabis-use
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.