Preliminary evidence of links between ayahuasca use and the corpus callosum

This neuroscience study (n=44) investigated the difference in thickness of the corpus callosum (the section that connects brain regions) of ayahuasca users (n=22) and those not using it. The corpus callosum was significantly thicker within the isthmus (one of the four sections) in the ayahuasca group. This effect was not significant after correcting for multiple comparisons.


Background: Recent research suggests that ayahuasca and its alkaloid-containing ingredients may be helpful in the treatment and prevention of certain movement and neurodegenerative disorders. However, such research is still in its infancy and more studies in normative samples seem necessary to explore effects of ayahuasca on clinically relevant brain structures, such as the corpus callosum.

Aims: The purpose of the present study was to investigate links between ayahuasca use and callosal structure in a normative sample.

Methods: Using structural imaging data from 22 ayahuasca users and 22 matched controls we compared the thickness of the corpus callosum between both groups at 100 equidistant points across the entire midsagittal surface. In addition, we investigated point-wise correlations between callosal thickness and the number of past ayahuasca sessions.

Results: The corpus callosum was significantly thicker within the isthmus in the ayahuasca group than in the control group. There was also a significant positive correlation between callosal thickness and the number of past ayahuasca sessions within the rostral body, albeit none of these effects survived corrections for multiple comparisons. No region was significantly thicker in the control than in the ayahuasca group, and no callosal region was negatively linked to ayahuasca use, even at uncorrected significance thresholds.

Conclusion: This study provides preliminary evidence of links between ayahuasca use and the corpus callosum. However, future studies need to replicate these findings, preferably using larger sample sizes and ideally also utilizing longitudinal research designs, to draw any practical conclusion and offer implications for follow-up clinical research.”

Authors: Otto Simonsson, José Carlos Bouso, Florian Kurth, Dráulio B. Araújo, Christian Gaser, Jordi Riba & Eileen Luders

Summary of Preliminary evidence of links between ayahuasca use and the corpus callosum

Ayahuasca is a psychedelic botanical admixture that is made by mixing Banisteriopsis caapi and Psychotria viridis. The -Carboline alkaloids in B. caapi and P. viridis prevent MAO-A from degrading DMT, which produces potent psychoactive effects.

Ayahuasca may treat various disorders, including multiple sclerosis, amyotrophic lateral sclerosis, and Parkinson’s disease, because it activates the sigma-1 receptor and several serotonin receptors.

Study details

Compounds studied

Topics studied

Study characteristics
Open-Label Re-analysis Bio/Neuro

44 Humans


Authors associated with this publication with profiles on Blossom

Otto Simonsson
Otto Simonsson is a Postdoctoral Research Fellow at the Karolinska Institute where he conducts research on meditation and psychedelics. Otto held a similar position at The Centre for Healthy Minds at the University of Wisconsin-Madison.

José Carlos Bouso
José Carlos Bouso is a Clinical Psychologist with a PhD in Pharmacology and is the current Scientific Director at ICEERS.

Jordi Riba
Jordi Riba (1968 - 2020†) was a pioneering ayahuasca researcher who dedicated over two decades of work to the field. His work focussed on the pharmacokinetics and pharmacodynamics of ayahuasca, including alkaloid disposition, and electroencephalography, and neuroimaging measures of acute ayahuasca effects. He also conducted several studies on centrally-acting drugs on the acute and long-term effects of psychedelics, psychostimulants, cannabinoids, sedatives, and kappa-opioid receptor agonists. His later work moved towards investigating the neural and psychological mechanisms that could underlie the beneficial effects of ayahuasca in the treatment of various psychiatric conditions.


Institutes associated with this publication

Karolinska Institutet
KI is Sweden’s single largest centre of medical academic research which as expanded into the field of psychdelics.

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Long-term use of psychedelic drugs is associated with differences in brain structure and personality in humans
This study (n=44) investigated the long-term effects of regular ayahuasca use on the human brain. Structural MRI showed that regular ayahuasca users had significantly different cortical thickness (with thinning in the posterior cingulate cortex) when compared to non-users. Although direct causation cannot be established, these data suggest that regular use of psychedelic drugs could potentially lead to structural changes in brain areas supporting attentional processes, self-referential thought, and internal mentation.

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