5.3 Ayahuasca
There is one observational study investigating the effects of ayahuasca on substance misuse and psychological functioning in 12 participants with no specific psychiatric or SUD.99 The intervention was a four-day retreat including two “ayahuasca ceremonies” (50-100mL of ayahuasca) and various addiction-related psychosocial intervention groups. As a major limitation, the diagnosis regarding opioid use (i.e., whether or not participants had OUD) entering the study was not reported; however, it is noted that some participants were receiving methadone treatment. The primary substance use measure was the Four-Week Substance Use Scale (4WSUS). Scores reportedly decreased for all substances except for cannabis; however, data on primary opioid use was not clearly reported. There was no observed difference in opioid use among participants when comparing the proportion who had used opioids at the baseline and the six-month follow-up. However, results showed statistically significant improvements in multiple psychological measures, including mindfulness, empowerment, hopefulness, quality of life-meaning, and quality of life outlook across the whole group — which is generally consistent with prior research on ayahuasca.100 Other studies on ayahuasca have also suggested its effects on decreasing substance use and potentially mitigating other negative psychosocial effects of drug use, which may deserve future attention.101 These themes also appear in qualitative work in those using ayahuasca for addiction-related issues in indigenous communities among whom SUD is prevalent.102 At this time, however, there are no currently registered ayahuasca trials for OUD or opioid dependence.