The main psychoactive component of cannabis seems to reduce persistent and distressing nightmares in people with post-traumatic stress disorder (PTSD). The drug dronabinol 鈥� purified tetrahydrocannabinol (THC) oil extracted from cannabis plants 鈥� 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 at some point in their lives. It causes people to repeatedly recollect a traumatic event, . Treatments like trauma therapy can help, but these aren鈥檛 always easily accessible, and no interventions specifically focus on relieving nightmares.
at the Charit茅鈥揢niversit盲tsmedizin 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. 鈥淭hat was the rationale [for the trial],鈥� he says.
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R枚pke 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 鈥� which is approved to treat nausea and vomiting caused by cancer drugs, and loss of appetite in people with acquired immunodeficiency syndrome (AIDS) 鈥� 1 hour before bed every night for 10 weeks. The remaining 84 participants took a placebo.听
They started on 2.5 milligrams and gradually increased the dose until their nightmares stopped or they reached the maximum 15 mg dose. R枚pke stresses people shouldn鈥檛 self-medicate with cannabis: 鈥淭reatment with dronabinol [and similar interventions] should be prescribed and monitored by a physician.鈥�
After 10 weeks, nightmare severity decreased by about 3.7 points in the dronabinol聽group 鈥� 1.5 points more than the placebo group. 鈥淎 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,鈥� says R枚pke.
鈥淏ased on the moderate effect size for the nightmares outcome, I would say the findings are clinically relevant,鈥� says 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. What鈥檚 more, 37 per cent in the former group experienced a complete cessation of their nightmares, compared with 15 per cent of the placebo group. 鈥淲hat impressed us most was the magnitude of the effect,鈥� says R枚pke.听
THC鈥檚 psychoactive effects meant that around 4 in 5 of the participants who took it gauged that they weren鈥檛 in the placebo group. However, half of those given a placebo thought they received dronabinol. Expectancy of an effect may explain some of the results, but probably not all of them, says R枚pke.
One idea is that THC alters signalling in the brain鈥檚 . This helps regulate processes and how brain cells communicate, which could lead to fewer nightmares. (REM) stage of sleep, when most vivid dreaming occurs, although studies on this have produced .听
鈥淚f they鈥檙e not dreaming as much, then they鈥檙e not going to have nightmares,鈥� says Cuttler. 鈥淭he problem is that if you discontinue using THC, there is an REM rebound, and you have really bad nightmares.鈥澛�
The researchers observed a small increase in sleep disturbances in the two-week follow-up period after the study ended. Cuttler says this could encourage nightly use of dronabinol, which doesn鈥檛 get to the root of someone鈥檚 PTSD. 鈥淭he symptoms come back once they sober up and that leads them to need to use more of the drug, and that can create a cannabis use disorder or dependence.鈥澛�
Seven people who received dronabinol experienced a serious adverse event, which the researchers say wasn鈥檛 caused by the treatment, compared with none in the placebo group.
Nature Medicine
