A double-blind trial found no statistically significant benefit from purified cannabidiol on key behavioural measures, despite some encouraging caregiver reports.
A clinical trial of purified cannabidiol in autistic boys with severe behavioural difficulties found no meaningful benefit on its main outcome measures, tempering hopes that CBD might offer a broadly effective treatment for this group. According to the study, published in the Journal of Autism and Developmental Disorders, the boys who received CBD did not improve significantly more than those given placebo on the trial’s primary behavioural scales.
The research used a double-blind, placebo-controlled crossover design, in which participants received CBD for eight weeks, then placebo after a washout period, or the reverse. The treatment dose was gradually increased from 5mg to 20mg per kilogram a day. Although the study began with 44 randomised participants, five were unable to complete blood collection before treatment started, leaving 39 boys in the main analysis, and 30 who finished the full 20-week protocol.
The main measures included the Repetitive Behaviour Scale-Revised, the Child Behaviour Checklist and the Autism Diagnostic Observation Schedule-2. Results on those tests did not show a significant difference between CBD and placebo. Both treatment periods were associated with improvement, and some caregiver reports were encouraging, but the gains were similar in both arms, making it difficult to attribute them to CBD itself. The paper noted that a larger numerical drop in repetitive-behaviour scores with CBD looked promising, but it did not cross the threshold for statistical significance.
The authors also pointed to several practical limitations that matter for interpreting the results. Withdrawals occurred for a range of reasons, including caregiver-reported behavioural changes, and the researchers said broad outcome measures may not have been ideally sensitive for this population. Even so, the trial adds to the evidence that placebo control is essential in autism treatment studies and suggests that future work may need more targeted measures if researchers are to identify whether some children could still benefit from purified CBD under specific conditions.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
