Study: Long-Term Use Of Ayahuasca Linked To Changes In Personality And Brain Structure

Ayahuasca is experiencing a global and cultural expansion similar to the growth and spread of yoga and meditation in the West over the past decades. This incredible healing medicine has blossomed in the consciousness of tens if not hundreds of thousands of worldwide seekers who travel to the Amazon to participate in ayahuasca ceremonies. Concomitant with this increased usage of ayahuasca is a growing output of scientific investigation into its effects on the human body and psyche.

Following up on a study conducted in 2012 in which researchers at the Sant Pau Institute in Barcelona evaluated the effects of long-term use of ayahuasca and provided evidence that ayahuasca does not cause long-term harm to its users, a similar team of researchers from Sant Pau has now looked into the long-term use of ayahuasca and its association with changes in brain structure and personality. Their findings were published in the journal European Neuropsychopharmacology in April 2015.

The team studied a group of 22 regular users of ayahuasca and compared magnetic resonance imaging (MRI) scans of their brains against 22 appropriately matched control subjects who have never used ayahuasca. The researchers used these MRI scans to measure cortical thickness, a valuable metric for assessing normal and abnormal neuroanatomy, which can provide information on normal brain development and disease progression. The regular users included in the study have been using ayahuasca in a ceremonial context at least 50 times in the past two years, which equates to participating in a ceremony once every other week. The researchers took great care to ensure that all study participants had no personal history of psychiatric or neurological disorders, had used cannabis 20 times or less and other drugs ten times or less. This was done so that any observable differences in brain structure or personality characteristics could be more likely attributable to ayahuasca use and not to some other factor.

After analyzing the MRI images, the researchers found that cortical thickness was altered in eight areas of the brain in the ayahuasca test group versus the control group. The most prominent difference observed was thinning in the posterior cingulate cortex, a part of the brain posited to be a central communication hub in a special brain network involved in high-level constructs such as the ego or self. Interestingly, the researchers also detected cortical thickening in the anterior cingulate cortex of ayahuasca users, an area of the brain believed to be involved in governing attention and cognitive control. In correlation analyses, the researchers observed that a higher frequency and number of years of use of ayahuasca is associated with a thinner posterior cingulate cortex.

In line with these findings were differences in scores between the ayahuasca test group and the controls with respect to aspects of personality and neuropsychology. Ayahuasca users scored significantly lower than controls in a personality trait characterized by pessimistic worry in anticipation of future problems and scored higher in self-transcendence, a characteristic exemplified by spirituality, religiousness, and expansion beyond one’s own boundaries to consider one’s self as an integral part of the universe as a whole. These higher scores in self-transcendence were associated to a thinner posterior cingulate cortex. “Thus,” the authors of the study state, “differences in this character dimension may have a neural basis and be the result of repeated intake of [ayahuasca].”

But how could ayahuasca lead to such observable changes in the brain?

The authors suggest that the structural differences could be the result of ayahuasca triggering a certain set of genes responsible for modulating the growth and flexibility of neural connections and suggest that, “it is plausible that the direct pharmacological action of DMT accounts for the observed structural differences after repeated exposure to ayahuasca.” DMT (N,N-Dimethyltryptamine) is the primary psychoactive ingredient found in ayahuasca preparations.

Aside from differences in self-transcendence and anticipatory worry, ayahuasca users also performed significantly better in neuropsychological tests (which assessed criteria such as memory, planning and set-shifting) than the controls, responding with a higher number of correct responses and lower number of errors. In fact, similar increases in cognitive performance were observed in ayahuasca users in a previous study. The authors suggest that these increases in performance may be attributable to the increased thickness of the anterior cingulate cortex in ayahuasca users. In further support of there being no long-term harm consequent to protracted use of ayahuasca, the researchers did not find any differences between the ayahuasca users and controls in any symptomatic aspect of psychopathology.

Although the research team observed several remarkable changes in brain structure, greater self-transcendence, and better cognitive performance in the ayahuasca test group relative to the controls, they were unable to establish a firm basis of causation because of the cross-sectional nature of the study. In other words, because the study only measured subjects at one particular point in time, they can only say that their data suggests that “regular use of psychedelic drugs could potentially lead to changes in brain tissue.”

Regardless of this caveat, the Sant Pau Institute researchers are firmly leading the way to a scientific understanding of ayahuasca’s impact on the human body, psyche, and spirit. Results from studies like this will help to provide an evidence-based approach to establishing safety standards and other considerations in the face of the global expansion of ayahuasca consciousness.