Post-traumatic stress disorder is marked by fear memories that do not fade. Even when a threat is gone, the brain continues to respond as if danger is present. This makes daily environments feel unsafe and keeps symptoms locked in place. A new preclinical study helps explain how ayahuasca may support PTSD fear extinction by targeting specific brain plasticity pathways involved in relearning safety.
Ayahuasca is a traditional Amazonian brew that contains the psychedelic compound DMT along with beta-carbolines that make DMT orally active. While human studies have suggested benefits for mood and trauma symptoms, the precise brain mechanisms have remained unclear. The new research takes a detailed look at how ayahuasca affects trauma-like fear memories under controlled laboratory conditions.
Why Standard Fear Models Fall Short
Most laboratory studies of fear extinction rely on mild conditioning that fades easily. PTSD, however, involves fear memories that are intense, persistent, and resistant to extinction. To better model this, researchers used stress exposure and high-intensity fear conditioning in rats to produce memories that resemble trauma-related fear.
In these models, animals not only struggled to extinguish fear in the original threatening environment but also showed fear generalization. This means they responded with fear in completely safe settings. Fear generalization is a core feature of PTSD and a major barrier to recovery.
Ayahuasca Improves Extinction and Reduces Overgeneralization
When rats received low-dose oral ayahuasca before extinction training, their behavior changed significantly. Stressed animals learned more quickly that a previously dangerous environment was now safe. They also showed less freezing behavior in neutral contexts, indicating reduced fear generalization.
Importantly, the dose used did not cause sedation, anxiety changes, or movement impairments. This suggests the effects were driven by learning and plasticity rather than nonspecific behavioral suppression. Both male and female animals showed improved extinction, highlighting a robust effect across sexes.
The Role of the Infralimbic Cortex and BDNF: Ayahuasca and Fear
To understand how ayahuasca produced these effects, researchers focused on the infralimbic cortex, a region of the medial prefrontal cortex known to regulate fear inhibition. This area helps suppress amygdala-driven fear responses once a threat is no longer present.
The study found that ayahuasca’s benefits depended on brain-derived neurotrophic factor, or BDNF. BDNF is a key protein that supports synaptic plasticity and learning. When researchers blocked BDNF signaling in the infralimbic cortex, ayahuasca no longer enhanced fear extinction. Blocking the TrkB receptor, which BDNF activates, produced the same result.
These findings provide strong evidence that ayahuasca promotes fear extinction by engaging BDNF-TrkB plasticity pathways in the prefrontal cortex.
Gender in Fear Generalization for Ayahuasca and Fear
An intriguing finding involved sex-specific effects. While blocking BDNF signaling prevented ayahuasca from reducing fear generalization in female rats, males retained this benefit even when the pathway was blocked. This suggests that different brain circuits may support fear discrimination in males and females.
These differences point toward the future possibility of more personalized trauma treatments that account for biological sex in both mechanism and response.
What This Means for PTSD Research
This study does not suggest that ayahuasca is ready for clinical PTSD treatment. The findings come from animal models and used carefully controlled doses. However, they offer valuable insight into how psychedelic compounds may reopen a window of plasticity that allows the brain to relearn safety.
By identifying a clear molecular pathway, the research supports the broader idea that psychedelic-assisted therapies may work by enhancing learning during extinction-based treatments rather than simply dampening symptoms. This mechanistic clarity helps guide future human studies and may inform safer, more targeted approaches to trauma care.
Citations
Werle I, Guimarães FS, dos Santos RG, Hallak JEC, Bertoglio LJ. Ayahuasca modulation of traumatic-like fear memories requires infralimbic cortex BDNF-dependent mechanisms in rats. European Neuropsychopharmacology. 2026. https://www.sciencedirect.com/science/article/abs/pii/S0924977X25007886
Ayahuasca and Fear: The Part No One ExplainsMilad MR, Quirk GJ. Fear extinction as a model for translational neuroscience: ten years of progress. Annual Review of Psychology. 2012;63:129–151. https://www.annualreviews.org/doi/10.1146/annurev.psych.121208.131631