New Evidence Marijuana (Cannabis) May Harm Teen Brain

by NCN Health And Science Team Posted on October 31st, 2018

Houston, Texas, USA : Teens who stop smoking marijuana (cannabis) can think and learn better afterward, even if they are only light users, a new study reports.Compared to teenagers and young adults who continued using marijuana, those who abstained for a month displayed a “modest but reliable improvement in their ability to learn,” said lead researcher Randi Schuster.

“Most of this improvement surprisingly happens rather quickly, within the first week of abstinence,” added Schuster, director of neuropsychology at Massachusetts General Hospital’s Center for Addiction Medicine.

The results show that kids need to be kept from using pot, Schuster said. This is a growing concern as recreational marijuana becomes legal in more U.S. states, she added.

“As we as a country move toward widespread legalization, we should pay attention to smart prevention programming for children,” Schuster said.

The researchers cited a 2016 survey that found almost 14 percent of middle and high school students had used pot in the prior month. It also showed daily use doubling between eighth and 12th grades.

Maturation of critical parts of the brain occurs in adolescence, and regular pot use in those years may cause more harm than later use, the researchers said in background notes.

Marijuana legalization proponents countered that the new study supports their contention that the effects of pot are temporary.

“These conclusions are consistent with those of prior studies finding that cannabis exposure is not likely to be associated with any sort of permanent adverse impact on the brain or cognitive performance,” said Paul Armentano, deputy director of NORML.

“These findings dispute the long-standing ‘stoner-stupid’ stereotype and should help to assuage fears that cannabis’ acute effects on behavior may persist long after drug ingestion, or that they may pose greater potential risks to the developing brain,” Armentano said.

For their study, Schuster and her colleagues asked two-thirds of a group of 88 marijuana users ages 16 to 25 to drop pot for a month.

The Boston-area participants were not all heavy users, but did use regularly. “We have kids using a minimum of one day a week or more,” Schuster said.

Urine tests revealed that 9 out of 10 participants did follow through on their promise to stop using pot for the study period.

Once a week, the young people took part in computerized brain games that tested their attention and memory, to see if stopping their pot use would help improve their brain function.

The computer tests showed that memory—specifically the ability to learn and recall new information—improved only among those who stopped using cannabis. The improvement occurred largely during the first week.

The study only showed an association between quitting pot and better learning ability, not a direct cause-and-effect relationship. Still, specialists are taking note of the findings.

“Cannabis use impacts learning and memory, and this study showed improvement in these domains after quitting,” said Dr. Scott Krakower, assistant unit chief of psychiatry at Zucker Hillside Hospital in Glen Oaks, N.Y.

“This research may motivate practitioners to encourage their patients to quit using marijuana and maintain abstinence,” Krakower said.

However, quitting marijuana did not appear to affect the participants’ ability to pay attention. Both groups performed similarly in that area.

Future studies will test whether this memory recovery brings marijuana quitters back to full function by comparing them with teens who’ve never used in the first place, Schuster said.

“What we don’t know is, by that one week are they back to the levels of their non-using peers, or is there a deficit that’s still measurable?” Schuster said.

The study appears in the Journal of Clinical Psychiatry.

Citation : Randi Melissa Schuster et al, One Month of Cannabis Abstinence in Adolescents and Young Adults Is Associated With Improved Memory, The Journal of Clinical Psychiatry. DOI: 10.4088/JCP.17m11977

A second study found that one month of abstinence from cannabis improves memory in adolescents and young adults

One month of abstinence from cannabis improves memory in adolescents, young adults

A Massachusetts General Hospital (MGH) study finds that one month of abstaining from cannabis use resulted in measurable improvement in memory functions important for learning among adolescents and young adults who were regular cannabis users. The study published in the Journal of Clinical Psychiatry is one of the first to prospectively track over time changes in cognitive function associated with halting cannabis use.

“Our findings provide two pieces of convincing evidence,” says Randi Schuster, Ph.D., director of Neuropsychology at the Center for Addiction Medicine in the MGH Department of Psychiatry, lead author of the paper. “The first is that adolescents learn better when they are not using cannabis. The second—which is the good news part of the story—is that at least some of the deficits associated with cannabis use are not permanent and actually improve pretty quickly after cannabis use stops.”

The authors note that the use of cannabis among adolescents is common, with more than 13 percent of middle and high school students reporting cannabis use in a recent survey and rates of daily use increasing between grades 8 and 12. But adolescence is a critical time for brain maturation, specifically for brain regions that are most susceptible to the effects of cannabis. A 2016 study from the same research team found that cannabis users aged 16 and under had difficulty learning new information, a problem that was not observed in users age 17 and older.

The current study is the first one able to determine not only whether cognitive improvement occurs but also when during abstinence this improvement is detectable. The study enrolled 88 participants ages 16 to 25 from the Boston area, all of whom acknowledged using cannabis at least once a week. Investigators compared weekly cognitive performance between a group of young cannabis users who agreed to stop their use for 30 days and a group that continued to use cannabis. To ensure that the two groups were as comparable as possible, they were randomized in a way that controlled for factors such as pre-existing differences in learning, mood, cognition and motivation, and the frequency and intensity of cannabis use.

Participants completed regular assessments of their thinking and memory during the study period. They also provided frequent urine tests to verify cannabis abstinence in those randomized to stop cannabis use and cannabis exposure in the continuing-use group. Members of both groups received incentive payments for study visits and among the abstinence group for adhering to cannabis abstinence.

Throughout the study period, the levels of the urinary cannabis biomarker steadily decreased among the abstinence group, with almost 89 percent meeting criteria for 30 days of continuous abstinence. In the continuing-use group, biomarker levels remained unchanged. Cognitive testing found memory—specifically the ability to learn and recall new information—improved only among those who stopped using cannabis, and this improvement occurred largely 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.

“The ability to learn or ‘map down’ new information, which is a critical facet of success in the classroom, improved with sustained non-use of cannabis.” Schuster says. “Young cannabis users who stop regular—weekly or more—use may be better equipped to learn efficiently and therefore better positioned for academic success. We can confidently say that these findings strongly suggest that abstaining from cannabis helps young people learn, while continuing cannabis use may interfere with the learning process.”

An assistant professor of Psychiatry at Harvard Medical School (HMS). Schuster adds, “There are still a lot of open questions to be studied, including whether attention might improve and memory continues to improve with longer periods of cannabis abstinence.” Those questions and others are being addressed in a larger follow-up trial that includes younger participants—ages 13 to 19—and a group that never used cannabis to help determine whether the cognitive improvements produced by cannabis abstinence return participants to performance levels similar to those of non-users. Another trial about to begin will follow young cannabis users who abstain for six months, investigating whether cognition continues to improve beyond 30 days and if those improvements can affect school performance.

Citation for second study : Randi Melissa Schuster et al, One Month of Cannabis Abstinence in Adolescents and Young Adults Is Associated With Improved Memory, The Journal of Clinical Psychiatry. DOI: 10.4088/JCP.17m11977

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