Start Rolling Your Blunts: New Study Says Weed Can Enhance Cognitive Function

We've already heard how medical marijuana can help people with everything from PTSD to creativity. Now there's even more evidence from Harvard-Tuft researchers in study indicating that cannabis helps our cognitive performance, i.e. the way we acquire and process knowledge.

Published in Frontiers in Pharmacology, the ongoing study, called "Splendor in the Grass? A Pilot Study Assessing the Impact of Medical Marijuana on Executive Function", tracked 24 medical marijuana patients over three months, during which their cognitive abilities were measured through certain mental challenges like the Stroop Color Word Test or the Trail Making Test.

The Stroop Color Word Test evaluates a patient's ability to inhibit overlearned, automatic responses, such as rapidly naming the color of a color word printed in a conflicting color ink (e.g. If the word red is printed in blue ink, say "blue" instead of "red"). In the Trail Making Test, patients are asked to connect dots to assess psychomotor functioning, visual scanning, and attention, while also asked to alternate between letters and numbers to measure cognitive flexibility.

According to a corresponding report by McLean Hospital, a Harvard Medical School affiliate, this study is the first of its kind to specifically look into medical cannabis' effects on cognitive performance "and related measures" by monitoring a patient's baseline cognitive performance before treatment and after three, six, and 12 months of medical cannabis treatment.

"After three months of medical marijuana treatment, patients actually performed better, in terms of their ability to perform certain cognitive tasks, specifically those mediated by the frontal cortex," said Staci Gruber, lead researcher and director of the Marijuana Investigations for Neuroscientific Discovery (MIND) program at McLean Hospital.

The researchers also noted a 42 percent decrease in opioid use among the study participants, improved sleep and overall health, especially in relation to depression and impulsivity. "This is significant, particularly for those of us in Massachusetts and other areas of the country where the opioid epidemic is ravaging so many," Gruber said.

She explained that in order to participate in the study, the subjects had to be "marijuana naive," meaning that they didn't already use it for recreational purposes; hence, they had to be new medical marijuana patients under Massachusetts' medical law.

The patients were recommended cannabis for whatever conditions they needed it, and used a variety of products, including vaporizers, edibles, topicals, and smoked flower. The cannabinoid levels also differed, based on a patient's needs, so some of the cannabis they were smoking might have had higher levels of the non-psychoactive CBD, while others had higher levels of THC or the cannabinoids CBG or THCA.

The researchers speak to the participants on the phone often, asking them to keep a log of their medicating habits. At the three month, six month, and 12 month markers, the patients come in for written tests and assessments looking at "decision making, inhibition, memory, psychomotor speed, and if eligible, neuroimaging," said Gruber.

The study's researchers laid out a few hypotheses as to why the patients in the study experienced improved cognitive functioning. Given that the patients also experienced improved general health, that may result in improved cognitive function, they suggested. "Symptoms commonly reported in medical marijuana patients including anxiety and pain have been associated with reduced cognitive performance," they wrote. "Symptom improvement may therefore result in improved cognitive performance."

They also hypothesized that the medical marijuana products, themselves, protected against "executive function deficits that have been widely reported in recreational marijuana users." The answer may be in the difference between medical and recreational marijuana products, such as the ratio of THC to CBD and other cannabinoids.

"Despite rapid changes in the law, many policy makers, consumers, physicians, and the general public remain misinformed about marijuana," the study's researchers wrote. Many questions about the effects of cannabis remain unanswered, and ultimately, until federal law changes to open up more research opportunities, it's unlikely the bulk of those remaining questions will be answered by American scientists.

This study, meanwhile, is still ongoing, so the results are not conclusive. And, it's important to note that the study was limited to 24 participants, all of whom do not use marijuana recreationally. But the findings add to a compendium of growing evidence that supports medicinal marijuana.

"One of the big things to take home from this study is that individuals who are medical marijuana patients aren't necessarily going to have serious cognitive decrements associated with cannabis use," Gruber said.

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