A pilot RCT of Sativex (THC:CBD spray) in 30 adults with ADHD found no significant improvement on the primary outcome but nominally significant improvements in hyperactivity/impulsivity and cognitive inhibition, providing the first experimental evidence for the self-medication theory.
Read this if you have ADHD and want to know what the first controlled study of cannabis for ADHD actually found.
Hyperactivity/impulsivity improved (p=0.03) but did not survive multiple testing correction
What the researchers found
In this pilot randomized, placebo-controlled trial, 30 adults with ADHD received either Sativex oromucosal spray (THC:CBD) or placebo. The primary outcome, cognitive performance and activity level measured by the QbTest, showed no significant difference, though active group scores were consistently better than placebo.
Secondary outcomes were more encouraging: Sativex was associated with nominally significant improvement in hyperactivity/impulsivity (p=0.03) and a cognitive measure of inhibition (p=0.05). Trends toward improvement were seen for inattention (p=0.10) and emotional lability (p=0.11). Per-protocol effects (excluding dropouts) were stronger.
However, results did not survive adjustment for multiple testing. One serious adverse event (muscular seizures/spasms) occurred in the active group.
Why it matters
Adults with ADHD frequently report self-medicating with cannabis, and some US psychiatrists prescribe it despite no prior controlled evidence. This is the first RCT to test cannabinoids for ADHD, and while not definitive, it provides preliminary experimental support for the self-medication theory by showing trends toward symptom improvement.
The numbers in context
30 participants (15 active, 15 placebo). Hyperactivity/impulsivity: p=0.03. Cognitive inhibition: p=0.05. Inattention: p=0.10. Emotional lability: p=0.11. None significant after multiple testing correction. 1 serious adverse event (muscular seizures) in active group.
How the study worked
Pilot randomized, double-blind, placebo-controlled trial (EMA-C trial). 30 adults with ADHD were randomized 1:1 to Sativex or placebo. Primary outcome: QbTest (computerized attention and activity measure). Secondary outcomes: ADHD symptom ratings and emotional lability. Recruitment: July 2014 to June 2015.
What this study cannot tell us
Very small pilot study (n=30) underpowered to detect modest effects. Primary outcome was not significant. Secondary outcome significance did not survive multiple testing correction. One serious adverse event. Short duration. Does not address long-term efficacy or cognitive effects of sustained use.
How to read the evidence
Pilot RCT with placebo control and blinding. Proper design but too small to be definitive. Results are hypothesis-generating rather than conclusive.
When this study was published
Published in 2017. This remains one of the only RCTs of cannabinoids for ADHD. Larger trials are needed.
The bigger picture
The relationship between cannabis and ADHD is complex. Cannabis acutely impairs attention and memory in most people, but adults with ADHD often report the opposite, that cannabis helps them focus. This trial suggests there may be a biological basis for this paradoxical response, though much larger trials are needed to confirm it.
Questions still open
- Would a larger trial confirm the trends seen here? Do specific cannabinoid ratios (higher CBD, different THC:CBD ratios) work better for ADHD? Are there ADHD subtypes that respond better to cannabinoids? How do cannabinoid effects on ADHD compare to standard medications?
Common questions
Does cannabis help ADHD?
Should people with ADHD use cannabis instead of their medication?
Read the original research
Cannabinoids in attention-deficit/hyperactivity disorder: A randomised-controlled trial.
European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology, 27(8), 795-808
Citation
Cooper, Ruth E; Williams, Emma; Seegobin, Seth; Tye, Charlotte; Kuntsi, Jonna; Asherson, Philip. (2017). Cannabinoids in attention-deficit/hyperactivity disorder: A randomised-controlled trial.. European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology, 27(8), 795-808. https://doi.org/10.1016/j.euroneuro.2017.05.005
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