Can low-dose THC dampen responses to stressful memories?

Details

Many cannabis users say they use it to relieve stress or dampen the effects of stressful memories, but how cannabis or its primary constituent, Δ9-tetrahydrocannabinol (THC), might alleviate stressful experiences remains unclear. Researchers tested whether low oral doses of THC reduce emotional or physiological responses to memories of a standardized social stress procedure in healthy volunteers.

In a double-blind study, healthy adults aged 18–35 were assigned to placebo, 5 mg THC or 10 mg THC groups, with 12 participants per group. The study had three sessions. In the first, participants completed the Trier Social Stress Test (TSST) and a non-stress control task to create individualized stress and neutral memory images. One week later, they received THC or placebo before viewing images from the first session. During this memory retrieval task, researchers measured subjective and physiological responses to stress and control images. In the third session, one week after the second, responses to the images were reassessed without administering a drug.

In the second session, TSST images significantly increased distress and arousal compared with control images. THC at either dose did not dampen most subjective or physiological responses to the images. The only measure on which THC reduced responses was emotional facial expressions during presentation of stress images. No lasting drug effects were observed in the third session.

This novel procedure produced images that elicited stress responses one week after the social stress procedure, but low doses of THC failed to reduce most subjective or physiological responses to stress-related images. The small sample raised questions about statistical power, although Bayes factor analyses supported the null findings. The researchers called for replication in larger samples.