Study shows marijuana could affect memory. What do you think?


COLUMBUS, Ohio – As Ohio employers decide whether their policies should accommodate workers who need medical marijuana, a new study shows adolescents and young adults who abstain from cannabis for a month have improved memory.

The Massachusetts General Hospital study, published in the latest issue of the Journal of Clinical Psychiatry, will likely be referenced among Ohio employers and educators as medical marijuana hits the market, which could be soon.

“It’s a good study,” said Gary Wenk, an Ohio State University Behavioral Neuroscience professor. ” It contributes a small amount of information.”

And its conclusions are consistent with previous research that shows young people’s brains are developing and they should not consume marijuana, said Wenk, who is a member of the Ohio Medical Marijuana Advisory Committee, which receives updates on the state’s program.

What the study doesn’t show, Wenk said, is differences in the amount of marijuana consumed and memory when the user stopped. A person who smokes one joint a week could have different results from someone who smokes three a day, he said.

“I have students who come to class every day high and do pretty well in their classes,” he said. “They could probably do better. But they have a lot of tolerance. Does it interfere with cognitive function of any kind? The answer has always been yes.”


Massachusetts General Hospital researchers studied participants ages 16 to 25 who said they used cannabis at least once a week.

They compared weekly cognitive performance between a group that agreed to stop using marijuana for 30 days with a group that did not. Urine tests confirmed people in each group were abstinent or using. Researchers randomized the two groups to control for factors such as differences in learning, mood, cognition and motivation, and frequency and intensity of marijuana use.

Cognitive testing found memory – specifically the ability to learn and recall new information – improved only among those who stopped using cannabis. The study improvement largely occurred during the first week of abstinence.

A month of cannabis abstinence was not associated with improvements in attention, and no aspect of cognitive functioning improved among those who continued cannabis use.

Ohio law only permits medical marijuana

Michael Gonidakis, a lobbyist in Ohio’s medical marijuana industry, reads the study as proof that Ohio’s rejection of recreational marijuana was wise. The medical marijuana program is more regulated than any recreational program would be. For instance, there are rules about what ailments people must have to legally possess it.

“The science and the medical community have proven with this study that recreational marijuana has a negative impact on a person,” he said. “The good news is that a person who quits smoking marijuana has a great likelihood of regaining cognitive function and living a healthy and normal life.”

Wenk, the Ohio State University professor, who teaches psychopharmacology and does preclinical research, said research shows that small amounts of marijuana – the equivalent to one puff a day — in older adults actually decreases pain and increases cognitive ability.

In fact, research has shown Baby Boomers widely considered “old hippies” have lower rates of Alzheimer’s Disease.

“If you start smoking a low dose, like one puff a day, after 50 or 55, there is a significant reduction in the incidence of Alzheimer’s,” he said.

Employers worry about safety

Michael E. Stanek also sits on the Ohio Medical Marijuana Advisory Committee. He thought the study was interesting, but he noted that there haven’t been a whole lot of double-blind studies about marijuana to understand all of its effects since it’s illegal federally and hard for researchers to obtain.

Still, the company he co-owns, Hunt Imaging, a toning manufacturer in Berea, will prohibit it.

“One of the biggest concerns from employers, and I speak from my background as a manufacturer, is having employees who are in safety sensitive positions who don’t have full faculties about them — whether it be from marijuana or any other pain killer that could cause their faculties to not be at 100 percent.”

Stanek sits on the board of the Greater Cleveland Partnership. He said his experience has mostly come from discussing medical marijuana with manufacturers in Northeast Ohio.

Other industries – such as those with office jobs that don’t require operating heavy machinery – may have different policies, he said.