Teens who are heavy users of marijuana may be setting themselves up for memory loss and physical changes in the brain suggests a new study.
Researchers found that young adults who'd smoked pot heavily as teens performed worse on memory tests than their peers who'd never used the drug regularly. And on brain scans, they tended to show differences in the shape of the hippocampus -the part of the brain that is involved with forming, organizing and storing memory.
The findings did not prove that heavy marijuana use caused the changes in the brain or memory dysfunction, but suggests that there could be a connection. The study was small and participants were only assessed once.
Matthew Smith, lead researcher and an assistant professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine, in Chicago, pointed out that other research has found a link between teenagers' heavy marijuana use and lingering memory problems, as well as a loss in IQ points. Similarly, brain-imaging studies have found that habitual pot smokers show differences in the volume and shape of the hippocampus, versus non-users.
The young adults had stopped smoking pot on an average of two years before participating in this study. Smith said that the brain changes and memory loss suggests that the effects may indicate long-term damage.
The current findings are based on 10 young adults who smoked pot heavily as teens -- usually daily, starting at 16 or 17, for an average of three years. Smith's team compared them with 44 young adults the same age, and from similar backgrounds, with no history of drug abuse.
Overall, the former marijuana users performed worse on a test where they had to listen to a series of stories, then remember as much information as possible a half-hour later.
Smith said he thinks the gap would be relevant in real life. "It would be similar to having a conversation, and then forgetting details 30 minutes later," he said.
The researchers also found a correlation between having an "oddly shaped" hippocampus and poorer memory performance, Smith said, though he added that does not prove the structural difference caused the memory issues.
Because teenager’s brain are still developing, Smith suggests that if young people want to smoke marijuana it might be best to wait until they are in their 20s before they start.
"The overall body of evidence is pretty clear that when teenagers use marijuana [regularly], their brains tend to look different and there tend to be cognitive differences," he said.
Not everyone agrees that this study points out a link between teenage heavy marijuana use with cognitive difficulties or hippocampus changes.
Paul Armentano, deputy director of NORML, a non-profit that advocates for legal marijuana use, says that because participants in the study were assessed only once, there’s no way to know whether the pot use came before any memory issues.
He also suggests other factors may be responsible for the hippocampus changes such as heavy drinking.
Armentano believes concerns about teenagers' developing brains presents a good argument for legalizing marijuana. "The obvious public-policy response," he said, "is to regulate the substance in a manner that better restricts young people's access to it, and provides them with evidence-based information in regard to its potential risks."
With the legalization of marijuana use in several states and other states looking at the possibility of legalization, more studies of the long-term effects are beginning to flow in.
Legalization certainly isn’t the beginning of pot use among teens. However, the perception of marijuana use as harmful is changing rather quickly among teens and even pre-teens.
According to www.drugabuse.gov, marijuana use remained stable in 2014, even though the percentage of youth perceiving the drug as harmful went down. Past-month use of marijuana remained steady among 8th graders at 6.5 percent, among 10th graders at 16.6 percent, and among 12th graders at 21.2 percent. Close to 6 percent of 12th graders report daily use of marijuana (similar to 2013), and 81 percent of them said the drug is easy to get.
Although marijuana use has remained relatively stable over the past few years, there continues to be a shifting of teens’ attitudes about its perceived risks. The majority of high school seniors do not think occasional marijuana smoking is harmful, with only 36.1 percent saying that regular use puts the user at great risk, compared to 39.5 percent in 2013 and 52.4 percent in 2009. However, 56.7 percent of seniors say they disapprove of adults who smoke it occasionally, and 73.4 percent say they disapprove of adults smoking marijuana regularly.
Waiting till a child has reached their pre-teen or teenage years to start discussing drug use isn’t going to be near as effective as beginning that conversation much earlier. Drugs have long held a fascination for kids whether you’re talking about marijuana, cigarettes, alcohol or any of the other type of inhalant or pills. That’s not news to parents. The difference is that drugs are now more easily available and new temptations are widespread.
No matter what the research eventually reveals, drug use should be a topic that parents start discussing with their children when they are young- using age-appropriate terminology- along with the sex, personal responsibility and ethics discussions. These conversations can provide information that will help them navigate peer and societal temptations in a more mature and educated way.
Sources: Amy Norton, http://teens.webmd.com/news/20150312/teens-heavy-pot-smoking-tied-to-memory-problems