Northwestern University scientists have identified a set of brain neurons that contribute to increased feelings of stress and anxiety after consuming cannabis, especially if the psychoactive cannabis consumption is paired with a stressful situation.
The team said their work offers scientific support for anecdotal claims of increased anxiety after cannabis consumption during highly stressful situations. They also suggested that their findings could open pathways for treating anxiety beyond cannabis users.
Cannabis Study Targets Connection Between Smoking cannabis, Stress & Anxiety
In recent decades, research into the potential benefits of controversial recreational drugs like cannabis and psilocybin has unearthed potential benefits and adverse effects that continue to drive more investigation. The potential medical benefits of THC, the active compound in cannabis, have received wider acceptance, leading to more than half of U.S. states permitting doctor-supervised use.
Still, while many medical users will cite benefits in combating depression, stress, anxiety, and even nightmares, anecdotal evidence has suggested that the plant’s ability to mitigate adverse mental health symptoms may depend on the circumstances. This includes reports from long-time users that cannabis can reduce stress in some situations, but amplify it in others.
According to the research team behind the new study, emergency room visits for adverse effects have increased alongside national cannabis use figures, also suggesting that the potential temporary psychological benefits or costs of smoking cannabis may depend on where you are and how you are feeling. They also cited research connecting long-term cannabis use to increased anxiety risk.
Dr. Sachin Patel, chair of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine and the lead author of a study detailing the team’s findings, said this duality motivated them to explore the role cannabis plays in anxiety regulation.
Drugged Mice Displayed More Fear and Avoidance Behaviors
To start, Dr. Patel and colleagues gave the laboratory mice either a synthetic cannabinoid drug or a placebo. Next, the animals were exposed to a threatening odor derived from fox urine, a natural predator.
When exposed to the odor, the ‘drugged’ mice froze more often than the placebo group. The cannabinoid test animals also spent significantly less time investigating the threatening odor than their sober companions.
The team monitored each mouse’s brain activity throughout the tests using small, implanted microscopes. After the tests, the researchers conducted brain tissue experiments to determine how cannabinoids affected communication between the brain’s neurons.
According to the team’s statement, these tests revealed that cannabis consumption weakened the brain’s natural “brake” on the somatostatin neurons in the amygdala. Previous studies have linked this brain region to fear and stress processing. Critically, the increase occurred in connection with the external odor threat, suggesting that the initial anxiety produced by the fear response, combined with the cannabinoid drug, rapidly escalates feelings of stress.
“Higher doses of cannabinoids and environmental stress worked together to synergistically release the ‘brake’ on the central amygdala, which in turn drove excessive anxiety,” Dr. Patel explained.
When the research team genetically “silenced” the somatostatin neurons in the drugged mice, they avoided the predator scent less than before, also suggesting a connection.
A Final Pathway for Reducing Anxiety Symptoms
When discussing the study’s results, Dr. Patel said their findings could “explain why a good trip can turn bad pretty quickly if people consume too much cannabis or the situation they are in turns stressful or scary.” The team leader also said the work could have anxiety-reducing benefits beyond cannabis use.
“Suppressing the activity of somatostatin neurons in the central amygdala could represent a final pathway for reducing anxiety symptoms, not just in the context of cannabis side effects,” he explained, adding that “understanding how cannabis affects brain function to generate its psychoactive effects could ultimately reveal new ways to counteract negative consequences should they arise in some people.”
Christopher Plain has spent the last six years as Associate News Editor and Head Science Reporter at The Debrief. Follow and connect with him on X, learn about his novels at plainfiction.com, or email him at christopher@thedebrief.org.