2003 – Pioneering Study Examines Ayahuasca Effects on the Body and Mind
In 1993, a team of researchers including Charles Grob and Dennis McKenna carried out pioneering research into the long-term effects of ayahuasca on users’ physical and psychological health. This was the first study that systematically studied the effects of ayahuasca in humans. Dr. Jordi Riba and associates added to this scientific inquiry into ayahuasca by performing a clinical trial in which they measured the psychological and physiological effects of ingesting ayahuasca. The participants were healthy and had previous experience with psychedelics on at least five occasions but no prior experience with ayahuasca.
Also, the study was double-blind and placebo-controlled, meaning that neither the researchers nor the participants knew if they were receiving the ayahuasca or the placebo. Double-blind, placebo-controlled studies are considered the gold standard of scientific research, as they help scientists to more accurately understand what the actual effects of a drug are. This study, therefore, was able to clarify how ayahuasca affected people’s minds and bodies.
Each participant took part in an experimental session four times, with sessions one week apart from each other. The researchers used a variety of questionnaires to find out what the subjective effects of ayahuasca were. These subjective effects included things like dizziness, lightheadedness, stimulation, increases in the speed of thoughts and/or change in thoughts processes and content, changes in visual perception (e.g. objects changing shape, colour, or brightness, or any abstract or elaborate hallucinations seen with eyes open or closed), alterations in how things sound, taste, and smell, and changes in emotional responses. In order to find out the physical effects of ayahuasca, Riba and the rest of the team measured blood pressure and heart rate and took urine and blood samples.
The researchers discovered that the brew produced perceptual distortions, elevated mood, and increased blood pressure when the heart was resting in between heartbeats, with insignificant changes in blood pressure during the heartbeat and heart rate. For the participants, subjective effects began around 30 to 45 minutes after ingesting the pills containing ayahuasca, peaking between 1.5 and 2 hours. This coincided with measurements showing when DMT was most concentrated in the blood, measured at 1.5 hours after ingestion. After 2 hours, the participants began to return to baseline, completely returning to baseline after 6 hours.
Based on the urine samples taken during the ayahuasca intoxication, the researchers found that there were alterations here too. They noted increased amounts of metanephrine and normetanephrine, a chemical that is made during the production of the hormone noradrenaline, otherwise known as the fight-or-flight hormone. The authors of the study concluded that the production of noradrenaline partly helped to explain the rise in blood pressure, as noradrenaline is a vasoconstrictor (meaning it narrows the blood vessels).
This study further supported the role of harmine as a substance that allows DMT to be taken orally. DMT is a potent psychedelic compound found in the chacruna plant (Psychotria viridis) that is used to make the ayahuasca brew. You can’t, however, just consume this plant by itself and experience an altered state of consciousness. This is because the body breaks down the DMT in the stomach by means of monoamine oxidase, a type of enzyme. But what indigenous people in the Amazon discovered is that if you combine chacruna with another plant containing a monoamine oxidase inhibitor (MAOI), the DMT becomes orally active. A commonly used MAOI-containing plant that achieves this effect is Banisteriopsis caapi. This vine, which contains harmine (an MAOI), inhibits the breakdown of DMT in the stomach, thereby enabling the DMT to enter the bloodstream and cross the blood-brain barrier intact, creating its powerful psychedelic effects.
Richard Evan Schultes, in earlier documentation of ayahuasca use, was aware that the effects of ayahuasca were due to the combination of different plants. This study from Riba and other researchers helped to confirm the exact role that the chemicals in these different plants served.
The scientific study represents one of the most pioneering scientific projects on ayahuasca. Others on such a list would have to include how the MAIO molecules in the ayahuasca vine allow DMT access to the blood stream through the gut; the safety profile of ayahuasca on drinkers; the positive long-term effects of ayahuasca on health; how the brain on ayahuasca and meditation behave similar to each other; how ayahuasca visions activate the brain similar to normal vision; and a study on the anti-depressant effects of ayahuasca, just to name a few.
Riba, J., Valle, M., Urbano, G., Yritia, M., Morte, A., & Barbanoj, M. J. (2003). Human pharmacology of ayahuasca: subjective and cardiovascular effects, monoamine metabolite excretion, and pharmacokinetics. Journal of Pharmacology and Experimental Therapeutics, 306(1), 73-83.