Ruth E. Cooper, Emma Williams, Seth Seegobin, Charlotte Tye, Jonna Kuntsi, Philip Asherson. Cannabinoids in attention-deficit/hyperactivity disorder: A randomised-controlled trial, European Neuropsychopharmacology, Volume 27, Issue 8, 2017, Pages 795-808. https://doi.org/10.1016/j.euroneuro.2017.05.005.
Rationale: Attention deficit/hyperactivity disorder (ADHD) affects about 5% of people worldwide. Changes in cannabis laws reflect changing public perception that the plant may have medicinal benefits, and some people advocate for the therapeutic effects of cannabis on ADHD. This study was the first experimental investigation to assess the effects of cannabis on ADHD symptoms.
Method: Researchers evaluated the effects of an oromucosal spray containing equal parts Delta-9 THC (THC) to cannabidiol (CBD) in 26 adults with ADHD on cognitive performance, activity level, and behavioral symptoms. The study took place over 6 weeks and was double-blind, randomized, and placebo-controlled, with 15 participants in the drug group and 11 in the placebo group.
Results: The cannabis treatment did not reduce hyperactivity or impulsivity, or improve attention in ADHD patients. Their performance on the Qb Test, a validated measure of ADHD symptoms, did not differ from those subjects receiving placebo treatment.
Meaning: This placebo-controlled experiment found no evidence of benefits from a 1:1 ratio of THC to CBD.