Effects of Cannabidiol on Social Relating, Anxiety, and Parental Stress in Autistic Children: A Randomised Controlled Crossover Trial

Cannabidiol (CBD), a non-intoxicating compound derived from the cannabis plant, has garnered increasing attention as a potential pharmacological therapeutic for autism. We conducted a randomized, double-blind, placebo-controlled, crossover trial to understand whether oral CBD oil containing terpenes can improve outcomes in autistic children. Twenty-nine children (18 male), aged 5 to 12 years (M=9.62 years, SD=2.05), diagnosed with autism spectrum disorder, completed the study. Participants received weight-based dosing of CBD oil (10 mg/kg/day) or matched placebo oil over two 12-week intervention periods (crossover), separated by an 8-week washout period. Outcome measures included the Social Responsiveness Scale-2 (SRS-2; primary outcome), PROMIS Social Relating, Anxiety, and Sleep, Developmental Behaviour Checklist-2 (DBC-2), Vineland-3, and Autism Parenting Stress Index (APSI; secondary outcomes). There was no significant effect observed for the primary outcome measure (SRS-2) for CBD oil relative to placebo oil after 12 weeks ({beta}=-11.15, SE=7.19, p=.125). Significant improvements were observed in secondary measures of social functioning, including DBC-2 Social Relating ({beta}=-2.35, SE=0.92, p(adj)=.024), as well as reduced anxiety on the DBC-2 subscale ({beta}=-3.20, SE=0.94, p(adj)=.002), and lower parental stress (APSI; {beta}=-4.63, SE=2.26, p(adj)=.044). No differences were detected on Vineland-3 adaptive functioning (ABC: {beta}=2.06, SE=2.67, p(adj)=1.000), and domain scores were not significant. Safety and tolerability data indicated that two children experienced gastrointestinal discomfort while taking CBD. Findings from this pilot trial suggest that while CBD combined with terpenes did not improve the primary outcome of social responsiveness, it may hold potential in addressing certain autism-related difficulties, particularly anxiety and social relating. Further research with larger sample sizes is needed to fully evaluate the efficacy and safety of CBD for autistic children. Lay SummaryThis pilot, exploratory study examined whether taking CBD oil could improve social outcomes for autistic children. While no significant changes were seen in overall social responsiveness, CBD led to improvements in specific social behaviours, reduced anxiety, and lowered parental stress. The treatment was generally well tolerated, though a few children experienced mild side effects. These findings suggest potential benefits of CBD for some autism-related symptoms, but larger studies are needed to confirm effectiveness.