Neuroscientist is Studying Long-Term Effects of Medical Marijuana

August 17, 2016

Staci Gruber vividly remembers her first hit of marijuana, back when she was in college.

It made her so paranoid, she locked herself in a bathroom. She couldn’t decide whether to remain in hiding or to run. But she knew she’d never try pot again.

She didn’t lose interest in the drug, however.

Today, she runs the 2-year-old Marijuana Investigations for Neuroscientific Discovery, or MIND , project at McLean Hospital in this suburb of Boston. With cognitive testing and neuroimaging, MIND is conducting a longitudinal study of medical marijuana.

“There’s a lot we don’t know about long-term effects, and that’s what I’m here to find out,” Gruber said.

Gruber, 49, has already made her mark on the field.

She ran a small study, published in 2013, that found teenagers and young adults who smoked marijuana were more likely to exhibit impulsive behavior than their peers and were more likely to have certain changes in the brain’s white matter. A followup study found that those changes could reorganize brain regions associated with inhibitions. This year, Gruber’s research team also found that chronic recreational users  of pot had poorer cognitive and executive functioning, particularly if they began using marijuana as teens.

MIND’s current work involves adults who are legally permitted to use marijuana-based products for medical conditions. The researchers are particularly interested in the non-psychoactive components of the marijuana plant, such as cannabidiol, an ingredient in many preparations of medical marijuana.

“We have this one word, marijuana, which we think means every part of the plant, and it doesn’t. The cannabinoids I study aren’t even the ones that get you high,” Gruber said. “But whether you’re for medical marijuana or against it, what we really need is information.”

Marijuana has been studied before. But previous research has focused on the cognitive effects of smoking pot recreationally. Earlier studies of medical marijuana have looked mostly at efficacy — how well it treats symptoms of conditions like multiple sclerosis, cancer, and HIV/AIDS.

Gruber and her colleagues, by contrast, are trying to determine the long- and short-term impact of medical marijuana on cognition, brain structure and function, quality of life, sleep, and other clinical measures.

“[This] is a primary concern for patients considering cannabinoid treatment, and it may have implications for public policy,” Gruber said.

Peering into the brain

The first phase of the MIND study is observational. Before patients begin their treatment, Gruber and her colleagues establish a baseline — using imaging, interviews, and task performance tests — to see what patients’ brains look like before they use medical marijuana.

The patients then record how much marijuana they’re using, and how often. At intervals of  three, nine, 12, 18 and 24 months, MIND researchers conduct more tests, brain scans, and interviews to measure the effects of the cannabis on their brain structures, cognition, and daily life.

This is the part of Gruber’s research that will be most valuable, said Madeline Meier, a marijuana researcher at the University of Arizona.

“The most important goal right now is to obtain high-quality data on the potential harms and benefits of cannabis,” Meier said.

There are currently 30 study participants; Gruber plans to enroll up to 200.  A separate MIND study will examine military veterans who use cannabinoids.

“People drive two to three hours sometimes to get [here for] the study,” Gruber said. “They’re really committed. They really want to know what effect this will have on them.”

As they wait for long-term results, MIND researchers have made a few interim discoveries. They have found, for example, that marijuana could possibly ease symptoms for people with bipolar disorder and that a medication for strokes and Alzheimer’s disease may reverse the cognitive effects of chronic recreational marijuana use.

Gruber’s earlier findings, raising red flags about the dangers of recreational pot smoking, have caught the eye of some activists, like the Seattle-based drug prevention program SAMA, short for Science and Management of Addictions.

“We brought her out here because she had done this great research on adolescents and THC,” said SAMA president Kim Brackett. “We call her ‘the rock star scientist.’ She has a very nice way of translating scientific information in a way that non-scientists can understand, from grandparents to 8-year-olds.”

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