Muted stress response linked to long-term cannabis use
A new study by Washington State University psychology researchers reveals a dampened physiological response to stress in chronic cannabis users.
Using a nationally recognized procedure designed to provoke elevated levels of stress, Carrie Cuttler, clinical assistant professor of psychology, Ryan McLaughlin, assistant professor of integrative physiology and neuroscience, and colleagues in the WSU Department of Psychology examined levels of the stress hormone cortisol in both chronic cannabis users and non-users.
“To the best of our knowledge, this is the first study to examine the effects of acute stress on salivary cortisol levels in chronic cannabis users compared to non-users,” Cuttler said. “While we are not at a point where we are comfortable saying whether this muted stress response is a good thing or a bad thing, our work is an important first step in investigating potential therapeutic benefits of cannabis at a time when its use is spreading faster than ever before.”
The WSU researchers found virtually no difference in the salivary cortisol levels of two groups of heavy cannabis users confronted with either a psychologically and physiologically stressful situation or a non-stressful one.
In contrast, cortisol levels among non-users of cannabis who experienced the same simulated stressful situation were found to be much greater than the cortisol level of non-users in the no-stress scenario.
The findings are consistent with a growing body of literature that indicates chronic cannabis use is associated with dulled adrenal and emotional reactivity. The study was published recently in the journal Psychopharmacology.
The stress test
Research participants self-identified as either a chronic cannabis consumer, with daily or nearly daily use for the previous year, or as a non-user who had consumed cannabis 10 or fewer times in their life and not at all within the previous year. Forty daily cannabis users and 42 non-users participated in the study. All were required to abstain from consuming cannabis on the day of testing.
Upon arrival at the lab, participants provided a saliva sample and were asked to rate their current level of stress. The chronic cannabis users and non-users were randomly assigned to experience either the high-stress or no-stress version of the Maastricht Acute Stress Test. Known by its acronym MAST, it is a commonly used procedure for stress-related research which combines elements of physical, psychosocial and unpredictable types of stress.
The no-stress version was simple: participants placed one hand in lukewarm water for 45-90 seconds and then were asked to count from 1 to 25.
The high-stress version upped the stakes significantly. Participants placed their hand in ice cold water for 45-90 seconds. They were then asked to count backwards from 2043 by 17 and were given negative verbal feedback when they made a mistake. On top of this, subjects were monitored by a web camera and the video feed was displayed on a screen directly in front of the participants so they couldn’t help but see themselves.
Immediately following the stress manipulation, all participants once again provided a saliva sample and were asked to rate their current level of stress. Before departing the testing facility, participants also provided a urine sample so researchers could corroborate self-reported use with bodily THC levels.
Interpreting the results
Cuttler and her colleagues’ work suggests cannabis may have benefits in conferring resilience to stress, particularly in individuals who already have heightened emotional reactivity to stressful situations.
However, the researchers emphasized the release of cortisol typically serves an adaptive purpose, allowing an individual to mobilize energy stores and respond appropriately to threats in the environment.
“Thus, an inability to mount a proper hormonal response to stress could also have detrimental effects that could potentially be harmful to the individual,” Cuttler said. “Research on cannabis is really just now ramping up because of legalization and our work going forward will play an important role in investigating both the short-term benefits and potential long-term consequences of chronic cannabis use.”
Next steps in the research will include investigating various factors, such as the presence of residual THC, which may be influencing the muted stress response in cannabis users.
A new study reveals a dampened physiological response to stress in chronic cannabis users. This is the first study to examine the effects of acute stress on salivary cortisol levels in chronic cannabis users compared to non-users.
Low-dose THC can relieve stress; more does just the opposite
Cannabis smokers often report that they use the drug to relax or relieve stress, but few studies provide clinical evidence of these effects.
Now, researchers at the University of Illinois at Chicago and the University of Chicago report that low levels tetrahydrocannabinol, or THC, the main psychoactive compound in marijuana, does reduce stress, but in a highly dose-dependent manner: very low doses lessened the jitters of a public-speaking task, while slightly higher doses — enough to produce a mild “high” — actually increased anxiety.
Cannabis is a highly regulated category 1 substance, and permits to study the drug are difficult to obtain. While it is common knowledge that many people use cannabis for its stress-relieving effects, “very few published studies have looked into the effects of THC on stress, or at the effects of different levels of THC on stress,” says Emma Childs, associate professor of psychiatry in the UIC College of Medicine and corresponding author on the study, published in the journal Drug and Alcohol Dependence.
“We found that THC at low doses reduced stress, while higher doses had the opposite effect, underscoring the importance of dose when it comes to THC and its effects.”
Childs and her colleagues recruited 42 healthy volunteers 18 to 40 years old who had some experience with cannabis use but who were not daily users.
Participants were randomly divided into three groups: The low-dose group received a capsule containing 7.5 milligrams of THC; the moderate-dose group received a capsule containing 12.5 milligrams of THC; and a placebo group received a capsule containing none. Neither the participants nor the researchers knew who was in each group.
“The doses used in the study produce effects that are equivalent to only a few puffs of a cannabis cigarette,” said Childs, noting that it is difficult to compare doses of smoked cannabis to doses of ingested THC. “We didn’t want to include a much larger dose, because we wanted to avoid potential adverse effects or cardiovascular effects that can result from higher doses of THC.”
Participants attended two four-hour sessions at the University of Chicago, five days apart. At each session, they took their capsule and then relaxed for two hours to allow the THC to be absorbed into the bloodstream.
During one session, participants were asked to spend 10 minutes preparing for a mock job interview. They were then subjected to a five-minute interview with lab assistants who did not offer any feedback, verbally or through body language, although video display was visible to the participant, showing their performance. Participants were then instructed to count backwards from a five-digit number by subtracting 13, for five minutes — a task that is “very reliably stress-inducing,” Childs said.
In their second visit, participants were asked to talk to lab assistants about a favorite book or movie for five minutes and then play solitaire for another five minutes.
Before, during and after each of the two activities, participants rated their stress levels and feelings about the tasks. Blood pressure, heart rate, and cortisol, a key stress hormone, were measured at intervals.
The participants who received 7.5 milligrams of THC reported less stress after the psychosocial test than those given a placebo, and their stress levels dissipated faster after the test.
Participants who received 12.5 milligrams of THC before the two tasks reported greater negative mood before and throughout the task, and were more likely to rate the psychosocial task as “challenging” and “threatening” beforehand. Participants who received this dose also had more pauses during the mock interview compared to those in the placebo group.
There were no significant differences in participants’ blood pressure, heart rate or cortisol levels — before, during or after the doses or the tasks.
“Our findings provide some support for the common claim that cannabis is used to reduce stress and relieve tension and anxiety,” Childs said. “At the same time, our finding that participants in the higher THC group reported small but significant increases in anxiety and negative mood throughout the test supports the idea that THC can also produce the opposite effect.”
“Studies like these — examining the effects of cannabis and its pharmacological constituents under controlled conditions — are extremely important, considering the widespread use of cannabis for both medical and non-medical purposes,” she said. “Unfortunately, significant regulatory obstacles make it extremely difficult to conduct this type of research — with the result that cannabis is now widely available for medical purposes with minimal scientific foundation.”
Low levels tetrahydrocannabinol, or THC, the main psychoactive compound in marijuana, does reduce stress, but in a highly dose-dependent manner, new research confirms.