THC in cannabis may reduce nightmares in people with PTSD

THC and CBD, active compounds in cannabis, are increasingly showing potential for relieving mental health conditions MAURO FERMARIELLO/SCIENCE PHOTO LIBRARY The main psychoactive component of cannabis seems to reduce persistent and distressing nightmares in people with post-traumatic stress disorder (PTSD). The drug dronabinol – purified tetrahydrocannabinol (THC) oil extracted from cannabis plants – was more than twice as likely to lead to a complete cessation of nightmares in people with the mental health condition than a placebo. Although it is unclear why it has this effect, THC may suppress the stage of sleep when dreams are most likely to occur. About 4 per cent of the global population have PTSD at some point in their lives. It causes people to repeatedly recollect a traumatic event, often through nightmares. Treatments like trauma therapy can help, but these aren’t always easily accessible, and no interventions specifically focus on relieving nightmares. Stefan Röpke at the Charité–Universitätsmedizin Berlin hospital in Germany sees people with PTSD every day and says some report getting relief from their nightmares if they take a small amount of cannabis before bed. “That was the rationale [for the trial],” he says. Röpke and his colleagues recruited 171 people with PTSD who experienced frequent, intense nightmares, assessed via a standard 0-to-8-point scale. Eighty-seven of the participants were instructed to take dronabinol – which is approved to treat nausea and vomiting caused , and loss of appetite in people with acquired immunodeficiency syndrome (AIDS) – 1 hour before bed every night for 10 weeks. The remaining 84 participants took a placebo.  They started on 2.5 milligrams and gradually increased the dose until their nightmares stopped or they reached the maximum 15 mg dose. Röpke stresses people shouldn’t self-medicate with cannabis: “Treatment with dronabinol [and similar interventions] should be prescribed and monitored by a physician.” After 10 weeks, nightmare severity decreased by about 3.7 points in the dronabinol group – 1.5 points more than the placebo group. “A 4-point improvement could mean having nightmares several times a week with considerable distress at baseline and having only occasional, mildly distressing nightmares after treatment,” says Röpke. “Based on the moderate effect size for the nightmares outcome, I would say the findings are clinically relevant,” says Carrie Cuttler at Washington State University. The researchers also found that 58 per cent of the dronabinol group experienced at least a 50 per cent reduction in their nightmare frequency and intensity, compared with 29 per cent of the placebo group.