(Medical Xpress)—A team of researchers from several institutions in Spain and Brazil has conducted test trials of a South American concoction known as ayahuasca to learn more about its impact on people suffering from depression. In their paper uploaded to bioRxiv the team describes the trials they conducted and what they found.
Two years ago, the same team conducted some initial tests to find out if ayahuasca reduced symptoms of depression—they reported back then that the results were promising. Seeking to expand on their work, the researchers undertook another test trial, this time enlisting the assistance of 39 volunteers, 14 of whom actually consumed the concoction, while the other 15 were given a placebo.
Ayahuasca has been known in South America for centuries, it is a beverage made by brewing two types of vines, Psychotria viridis, which contains a hallucinogenic compound, and Banisteriopsis caapi, which prevents the mind-altering compound from being broken down before it has time to pass from the gut to the brain. The result is a brew that by all accounts tastes quite nasty, and in some cases causes people to vomit. But it also induces a mind-bending experience. Anecdotal evidence has also suggested that it can improve symptoms for people suffering from depression, which led to the first and now second trial.
Each of the volunteers suffered from chronic depression, and each was asked to fill out a questionnaire regarding their mood the day before being given a single dose of ayahuasca (or an equally nasty-tasting concoction created as a placebo). On the day of dosing, each was given a small amount of ayahuasca or the placebo, and were kept in a safe room for four hours, which was how long it takes for the effects to subside. Each of the volunteers were then asked to again fill out the same questionnaire a day later, then two days later, and then a week after the trial.
The researchers report that both groups reported relief from symptoms one and two days after the trial, which is common for depression drug trials. But after a week, 64 percent of those given ayahuasca reported a reduction in symptoms of approximately 50 percent, compared to just 27 percent for those given a placebo.
Explore further: Substance present in ayahuasca brew stimulates generation of human neural cells
More information: Rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression: a randomised placebo-controlled trial, bioRxiv, biorxiv.org/content/early/2017/01/27/103531
Major Depressive Disorder affects about 350 million people worldwide, and about one-third of the patients are considered treatment-resistant. Furthermore, available antidepressants take usually two weeks for the onset of their antidepressant effect. Recent open label trials show that psychedelics, such as ayahuasca and psilocybin, hold promise as fast-onset antidepressants. Although promising, these studies were not controlled for the placebo effect. To address this issue, and to further test the antidepressant effects of ayahuasca, we conducted a parallel arm, double blind randomised placebo-controlled trial, in patients with treatment-resistant major depression. Thirty-five patients with treatment-resistant major depression received a single dose of ayahuasca or placebo. We measured as primary outcome the change in the Hamilton Depression Rating scale (HAM-D) seven days after the dosing session, and as secondary outcomes the changes in Montgomery-Asberg Depression Rating Scale (MADRS), and response rates at one day (D1), two days (D2) and seven days (D7) after dosing, and remission rates at D7. This study is registered with clinicaltrials.gov (NCT02914769). We observed robust evidence of rapid antidepressant effects of a single dosing session with ayahuasca when compared to placebo. HAM-D scores at D7 were significantly lower in patients treated with ayahuasca than in those treated with placebo (p=0.019; Cohen's d=0.98). MADRS scores were significantly reduced in the ayahuasca group compared to the placebo group at all endpoints (at D1 and D2, p=0.04; at D7, p<0.0001). Between-group effect sizes increased from D1 to D7 (D1: Cohen's d=0.84; D2: Cohen's d=0.84; D7: Cohen's d=1.49). Response rates were high for both groups at D1 and D2, and were significantly higher in the ayahuasca group only at D7 (64% vs. 27%; OR = 4.95; p = 0.04; NNT = 2.66). Remission rate was not significantly different between groups. Our study provides new evidence of rapid antidepressant effects of ayahuasca for treatment-resistant major depression.