SC Connecticut News

Yale researchers have identified a link between endocannabinoids and emotional numbing in individuals with post-traumatic stress disorder (PTSD). The study, published on September 9 in JAMA Network Open, found that higher levels of cannabinoid receptors in the amygdala were associated with reduced reactions to pain and greater emotional numbing.

“The endocannabinoid system is crucial for pain modulation and is involved in stress-related disorders like PTSD,” said Nachshon Korem, an associate research scientist at Yale School of Medicine (YSM) and lead author of the study. “Based on our earlier findings, we suspected it might contribute to this low reactivity of the amygdala.”

Korem is part of Ilan Harpaz-Rotem's lab, a professor of psychiatry at YSM and senior author of the study.

The researchers utilized PET scans to measure cannabinoid receptor 1 availability in the amygdala, fMRI to assess the amygdala’s reactivity to mild shocks, and clinical assessments to gauge participants' emotional numbness. The study included 30 trauma-exposed adults, nine of whom had PTSD diagnoses.

“We found that the more cannabinoid receptor 1 availability was in the amygdala, the less reactive the amygdala was to mild pain and the more emotional numbing symptoms a person presented,” Korem explained. “Endocannabinoids have a large inhibiting effect on the amygdala, and here it seems that when there is more receptor availability, endocannabinoids can suppress the amygdala’s response to mild pain more strongly.”

The findings suggest that targeting the endocannabinoid system could help manage PTSD symptoms by promoting appropriate reactions to minor irritations. This approach may prevent exaggerated responses commonly seen in PTSD patients.

“If you can help people with PTSD have appropriate reactions to smaller irritations, maybe it would prevent the sort of all-or-nothing responses common in the disorder,” said Korem. “The endocannabinoid system might be a target for that type of treatment.”

Future research will focus on pharmacologically targeting this part of the endocannabinoid system and exploring interactions between endocannabinoids and opioids.

Other authors involved in this study include Ansel Hillmer, Deepak Cyril D’Souza, Anahita Bassir Nia, Ifat Levy, and Robert Pietrzak from Yale School of Medicine.