Preliminary evidence of links between ayahuasca use and the corpus callosum

Abstract

BackgroundRecent 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.AimsThe purpose of the present study was to investigate links between ayahuasca use and callosal structure in a normative sample.MethodsUsing 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.ResultsThe 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.ConclusionThis 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.

Neural Network Modulation of Ayahuasca: A Systematic Review of Human Studies

“…One article [16] evaluated the effects of ayahuasca in patients with major depressive disorder and did not specify previous use by the volunteers. Acute effects were investigated in 8 studies [11][12][13][15][16][17][18][19], subacute effects in 1 study [20], and long-term effects in 2 studies [14,21]. The results found are consistent in demonstrating that there were brain anatomical and functional changes caused by ayahuasca in acute or chronic consumption.…”

“…Results were divided into neuroimaging techniques (SPECT, MRS, MRI, and fMRI). In 10 articles, the volunteers were healthy, with previous experience with ayahuasca [11][12][13][14][15][17][18][19]21] or without previous experience [20]. One article [16] evaluated the effects of ayahuasca in patients with major depressive disorder and did not specify previous use by the volunteers.…”

“…Regarding clinical trials, four different articles used the same sample of volunteers, differing in the types of data analyzed [13,15,18,19]. Concerning observational studies, two articles used the same sample of volunteers [14,21]. We will discuss the results in detail in the following paragraphs.…”

“…Therefore, a total of five new articles that were not present in our last review were included. Of these included papers, one used magnetic resonance spectroscopy (MRS) [17], three used functional magnetic resonance imaging (fMRI) [18][19][20], and one used magnetic resonance imaging (MRI) [21]. A flow diagram illustrating the different phases of the systematic search update from 2016 to 2022 is presented in Figure 1.…”

“…Simonsson et al, 2022 [21], using the same sample as Bouso et al, 2015 [14], sought to investigate links between ayahuasca use and callosal structure. They compared the thickness of the corpus callosum using structural imaging data from 22 ayahuasca users and 22 matched controls.…”