For a substance that has been used by humans for more than 5,000 years, there remains much to learn about marijuana’s effects on the brain. McLean neuroscientist and clinical researcher Staci Gruber, PhD, has spent more than two decades trying to advance knowledge in this domain.
Now, with the help of a $1.5 million grant from the Patricia Cornwell Foundation, a nonprofit organization created by the best-selling crime writer, Gruber has begun a first-of-its-kind, double-blind, randomized clinical study—the gold standard of scientific investigations—looking at the effects of a cannabis-based product on people with anxiety. Following an open label phase, the study will compare people taking a cannabis-derived sublingual tincture her lab spent years developing to those taking a placebo.
“Over time, we will look at their clinical symptoms—their levels of anxiety and depression, sleep, cognitive performance, quality of life, and their use of conventional medications,” explained Gruber. “We’ll also use neuroimaging to examine potential effects on measures of brain structure and function.”
Gruber, an associate professor of psychiatry at Harvard Medical School, is director of the MIND program—Marijuana Investigations for Neuroscientific Discovery—which seeks to fill gaps in understanding the impact of medical marijuana on cognitive function, mood, quality of life, medication use, and measures of brain structure and function. “This is the most important area I’ve explored in my career,” said Gruber. “We need to understand cannabis more fully—especially when intended for medical purposes.”
The first phase of Gruber’s ongoing longitudinal study, launched four years ago, put MIND on the medical marijuana research map. This first-ever, multiyear observational investigation has been following patients who use medical cannabis for a range of medical and psychological conditions. Using cognitive assessments, clinical measures, and neuroimaging techniques, Gruber and her colleagues reported patients’ improvements in sleep quality and executive function—the ability to manage life’s tasks—as well as other measures of mood and quality of life following three months of treatment. Patients also reduced their use of conventional medications, including a notable drop in their use of opioids.
Improvement on certain cognitive tasks after using medical cannabis stands in contrast with the majority of findings suggesting that recreational marijuana use is linked to decrements in cognitive abilities.
The longitudinal investigation has spun off related studies of veterans, investigating how medical cannabis affects PTSD, pain, anxiety, and other common conditions. “Veterans are a highly understudied population, often struggling with conditions reported to be addressed or partially ameliorated by cannabis,” said Gruber. “They offer an extraordinary opportunity to learn more.”
The Marijuana Landscape
Medical marijuana is now legal in 30 states and Washington, DC, while recreational use is legal in nine states and DC. Gruber frequently consults with policy makers and other stakeholders around the country about all sorts of questions, for example, the relative effects of different products and delivery systems (concentrates vs. flower, vaping vs. ingesting) and how much cannabis someone must ingest to be considered impaired. “We’re trying to let the science guide us, not the politics, not the emotion,” said Gruber.
The Cornwell Foundation has been a major supporter since MIND was established and in turn has inspired gifts from other foundations as well as industry. “The highly innovative MIND program has already made significant contributions to our knowledge of medical marijuana,” said author and McLean National Council member Patricia Cornwell. “We are confident our continued support will facilitate groundbreaking discoveries.”
Gruber said that this gift allows MIND to move into the next stage of its work, which includes projects focused on pain, mood, substance use, and other conditions, including those that disproportionately affect women. “Given the shifting landscape of marijuana use and legislation across the country, studies like these are critical, as they will undoubtedly shed light on the impact of medical marijuana and should help to both inform alternative courses of treatment and prevent unnecessary exposure, ultimately improving people’s lives.”
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