A pilot randomised placebo-controlled trial of cannabidiol to reduce severe behavioural problems in children and adolescents with intellectual disability

Br J Clin Pharmacol. 2021 Feb;87(2):436-446. doi: 10.1111/bcp.14399. Epub 2020 Jul 1.


Aims: Severe behavioural problems (SBP) are a major contributor to morbidity in children with intellectual disability (ID). Medications used to treat SBP in ID are associated with a high risk of side effects. Cannabidiol has potential therapeutic effects in SBP. This pilot study aimed to investigate the feasibility of conducting a randomised placebo-controlled trial of cannabidiol to reduce SBP in children with ID.

Methods: This is a double-blind, placebo-controlled, two-armed, parallel-design, randomised controlled trial of cannabidiol in children aged 8-16 years with ID and SBP. Participants were randomised 1:1 to receive either 98% cannabidiol in oil (Tilray, Canada) or placebo orally for 8 weeks. The dose was up-titrated over 9 days to 20 mg/kg/day in two divided doses, with a maximum dose of 500 mg twice/day. The feasibility and acceptability of all study components were assessed.

Results: Eight children were randomised, and all completed the full study protocol. There were no serious adverse events or drop-outs. Protocol adherence for key study components was excellent: study visits 100%, medication adherence 100%, blood tests 92% and questionnaire completion 88%. Parents reported a high degree of acceptability with the study design. All parents reported they would recommend the study to other families with children with similar problems. There was an efficacy signal in favour of active drug.

Conclusions: The findings suggest that the study protocol is feasible and acceptable to patients with ID and SBP and their families.

Keywords: cannabidiol; intellectual disability; irritability; medicinal cannabis; severe behaviour problems.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Canada
  • Cannabidiol*
  • Child
  • Double-Blind Method
  • Humans
  • Intellectual Disability* / drug therapy
  • Pilot Projects
  • Problem Behavior*


  • Cannabidiol