illustration of a person breaking apart
The negative effects of marijuana increased with the amount of cannabis used.

Marijuana can worsen depression, anxiety and cognition among people who use cannabis to help with their chronic pain, according to a new study. Negative effects increased with the amount of cannabis used, said the study, published recently in the journal Pain Management Nursing.

Lead Investigator Marian Wilson, a registered nurse and an assistant professor at the Washington State University College of Nursing, said the survey of 150 adults indicates concerning patterns that warrant further study.

Adults with persistent pain frequently say they use cannabis to help manage their symptoms. Among the reasons are that it’s perceived to be safer than using opioids and is readily accessible in many states.

The study sought to understand whether cannabis use affected cognition in patients with chronic pain and pre-existing anxiety and depression.

Participants, who also were prescribed an opioid medicine for their pain, self-reported clear or foggy thinking, their marijuana use, and symptoms of depression and anxiety.

The patterns indicate it’s likely that for at least some people with chronic pain, depression and anxiety are not helped by cannabis use, Wilson said.

“When people have depression and anxiety and use cannabis on top of this, it would appear they have more negative outcomes,” she said. “Is it that they’re using more cannabis because the pain is so bad and their mood is affected, or is it because people with depression and anxiety are at greater risk of using cannabis in a way that may not be therapeutic?”

Marian Wilson
Marian Wilson

She added, “What’s more likely is people with these mental health symptoms are using more cannabis and it’s not helping with those problems and is worsening cognition.”

Wilson said additional studies are needed to fully explain the relationships between symptoms and marijuana use that were detected in the survey study. Future research could demonstrate whether alternatives such as counseling can help patients with persistent pain manage their mental health without negatively affecting cognition.

The survey results also heighten the point that health care professionals should screen more aggressively for anxiety and depression among patients who use marijuana as a medical treatment. Study participants had high levels of anxiety and depression despite being under medical supervision for pain management with opioid treatment.

The study suggested further investigation into whether specific CBD and THC content worsens cognition and/or depression, and whether people with cognitive impairments and altered mood are more likely to choose cannabis as a pain treatment option.

“Because cognition might be further affected by chronic pain, depressive symptoms, and the prescribed opioids our study participants were receiving, these are important issues to explore,” it said.

Study: “Cannabis Use and Cognition in Adults Prescribed Opioids for Persistent Pain,” Megan Wildes, DNP, FNP-BC; Teresa L. Bigand, PhD, MSN, CMSRN, CNL; Matthew E. Layton, MD, PhD, FACP, DFAPA; Marian Wilson, PhD, MPH, RN-BC, published in Pain Management Nursing 21 (2020) 94-99.

–Story by Addy Hatch