New research from CU Boulder suggests that cannabis products rich in CBD, a non-intoxicating compound, may be more effective at reducing anxiety than THC-dominant products, without the risk of side effects. The study, involving 300 participants, is the first randomized trial examining the impact of legal cannabis on anxiety symptoms.
This study arrives at a crucial time, with anxiety disorders affecting one in five U.S. adults, making it the most common mental illness. Prescriptions for anti-anxiety medication are rising.
“We need more data to fully understand the long-term benefits, but the short-term effects were clear: CBD was linked to relief from tension and anxiety with minimal side effects,” said Cinnamon Bidwell, senior author and associate professor at CU Boulder’s Department of Psychology and Neuroscience.
First Randomized Trial on Cannabis and Anxiety
Adults commonly cite anxiety, alongside sleep and pain, as one of the top reasons they turn to cannabis for relief. However, previous research has shown mixed results, with some studies indicating that frequent use of THC-rich products could exacerbate anxiety over time. Other studies have suggested that adding CBD to THC-heavy products can counterbalance the negative effects, such as impairment and paranoia.
To explore these effects more thoroughly, the CU Boulder team recruited 300 adults with anxiety. Of these, 42 had never used cannabis, while 258 had prior experience. Participants were assigned to one of three product categories: THC-dominant (24% THC, 1% CBD), CBD-dominant (24% CBD, 1% THC), or a balanced product with equal parts THC and CBD (12% of each).
Due to federal restrictions, participants purchased their assigned products from dispensaries and used them off-campus. They could consume cannabis as often as they wanted over a four-week period, averaging three sessions per week.
Researchers tested participants before and after cannabis use at their homes using a mobile laboratory.
Key Findings
At the study’s end, all groups reported reduced anxiety, with cannabis users experiencing greater relief than the non-cannabis group. Among cannabis users, those in the CBD-dominant group saw the most significant improvements.
Interestingly, while the CBD group did not feel impaired after use, they experienced reduced tension and were less likely to feel paranoid compared to the other cannabis groups.
“Our results suggest that THC didn’t increase anxiety long-term, and CBD-dominant products were associated with short-term tension relief that may contribute to sustained anxiety reduction,” said Gregory Giordano, a research assistant at CU Boulder.
Bidwell also noted that CBD’s strong anti-inflammatory properties could play a role in anxiety relief, possibly by reducing inflammation in the brain. However, even a small amount of THC (1%) can quickly impact mood.
Prescription drugs for anxiety are widely available, but they can have side effects and lead to dependency. Early and frequent use of THC has also been linked to cannabis-related risks, including cognitive issues.
“This study suggests that CBD products could relieve anxiety in the short term and potentially in the long term without the risks associated with THC or prescription medications,” Bidwell said. “While more research is needed for definitive recommendations, this is promising.”
