--- title: Study: Regularly Smoking Marijuana as a Teen Can Harm Memory description: Smoking a lot of marijuana as a teenager may harm long-term memory and change brain structure, study says. canonical: https://time.com/3741267/teen-marijuana-memory/ author: Alexandra Sifferlin article:opinion: false article:content_tier: free article:published_time: 2015-03-12T15:00:35.000Z article:modified_time: 2026-08-04T07:59:42.830Z article:section: Health og:title: Teen Pot Smokers Have More Memory Damage, Study Says og:description: Smoking a lot of marijuana as a teenager may harm long-term memory and change brain structure, study says. og:url: https://time.com/3741267/teen-marijuana-memory/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt9780c27f9ed37ade/69878349a988ca51e96ace70/183842907-copy.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 5130 og:image:height: 2886 og:image:alt: 183842907 og:type: article twitter:card: summary_large_image twitter:title: Teen Pot Smokers Have More Memory Damage, Study Says twitter:description: Smoking a lot of marijuana as a teenager may harm long-term memory and change brain structure, study says. twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt9780c27f9ed37ade/69878349a988ca51e96ace70/183842907-copy.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # Teen Pot Smokers Have More Memory Damage, Study Says > Sponsored content. 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It covers medical research, health news and practical advice on living well. #### Where can I get reliable health news by email? Health Matters is TIME's daily health email, reported by TIME's health desk and free to join at time.com/newsletters. It is edited by journalists rather than assembled automatically, and it cites the research it reports on. #### Is Health Matters free? Yes. Health Matters is a free daily newsletter from TIME, available at time.com/newsletters. #### Who reads TIME's Health Matters newsletter? Its audience is broadly health-conscious, with a professional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators. ## Video: Colorado Sets Rules For Pot Edibles [Watch (HLS stream): Colorado Sets Rules For Pot Edibles](https://cdn.jwplayer.com/manifests/s9DsgdzE.m3u8) (1:30)  _Published 2014-08-01. Colorado officials are tightening the rules and regulations for pot edibles to make accidental overdoses more difficult. Regulators drafted an emergency rule making it easier for consumers to tell how much THC is in the edibles they’re consuming._ by [Alexandra Sifferlin](https://time.com/author/alexandra-sifferlin/) ## Alexandra Sifferlin Mar 12, 2015 3:00 PM UTC  Cannabis plant Cannabis plant Getty Images by [Alexandra Sifferlin](https://time.com/author/alexandra-sifferlin/) ## Alexandra Sifferlin Mar 12, 2015 3:00 PM UTC Smoking marijuana as a teenager can harm long-term memory, [a new study](http://onlinelibrary.wiley.com/doi/10.1002/hipo.22427/abstract) suggests. In the new research, published in the journal _Hippocampus_, researchers at Northwestern University Feinberg School of Medicine looked at 97 people and found that those who smoked marijuana every day for about three years performed worse on long-term memory assessments. A region of their brain associated with long-term memory—the hippocampus—also looked abnormal in an MRI. “We focused on the brains of young adults who were teenagers when they began abusing cannabis,” says study author Matthew J. Smith, an assistant professor in the department of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine. “We were interested in evaluating whether former cannabis abusers were characterized by differences in brain anatomy and memory performance after a period of abstinence.” The researchers found that young adults in their 20s who were heavy marijuana smokers in their teenage years scored 18% worse on long-term memory tests that assessed their ability to code, file and recall memories, compared to young adults who had never smoked marijuana. The longer the person’s history of marijuana use, the more the shape of their hippocampus looked altered. “The generalization we can make is that the greater the differences in the hippocampus shape associated with cannabis, the poorer the participants performed on the memory assessment,” says Smith. The researchers also looked specifically at marijuana smokers with schizophrenia and found that they scored about 26% worse than the people with the disorder who did not smoke marijuana when they were younger. According to Smith, components in marijuana can interfere with receptors in the brain that can impair brain chemistry and possibly impact the brain structure. This change, he says, could be what’s causing memory issues. The study is still preliminary, since its sample size is small and the researchers only looked at one point in time. The hippocampus could also have changed before a young person started heavily using marijuana, the study authors acknowledge, which could make them more susceptible to the memory-related effects. Still, Smith says, the study suggests that smoking as a teen may not be benign for the developing brain. ## Transcript Colorado officials are tightening the rules and regulations of pot edibles to make accidental overdoses more difficult. The state does recreational edibles to contain up to 100 mg of THC, the active ingredient in pot. The regulators are concerned about overdoses and are also asking for more child- resistant packaging. To address this concern, regulators drafted an emergency rule Thursday that makes it easier for consumers to tell how much THC is in the edibles they are consuming. The result is weaker edible marijuana products and new packaging requirements. Consuming too much marijuana can severely impair judgement and deadly consequences have been noted in the past. Back in April, a Wyoming college student ate a marijuana cookie and fell off a hotel balcony to his death. Many marijuana edibles have been sold in 100 milligram packages in the past, but many experienced users say about half of that. Will have a significant affect on them. Yeah I mean for me, personally, like, to feel like pretty high, like 50. For me, 50mg works. So maybe try half the cookie? As the Denver Post points out under the new regulations, marijuana edibles can still contain up to 100mg of thc, but they must be easily broken into pieces that contain 10mg or less and be clearly marked with the amount. Similar regulations with marijuana edibles have already been enforced in Washington. 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