Written by Honor Whiteman Published:12 November 2016
Researchers have long suggested marijuana can cause memory loss. Now, a new study provides insight on this association, revealing how cannabinoids in the drug activate receptors in the mitochondria of the brain's memory center to cause amnesia.
Researchers have shed light on how cannabinoids affect the brain to cause memory loss.
Study leader Dr. Giovanni Marsicano, of the University of Bordeaux in France, and team believe their findings - published in the journal Nature - may lead to the development of new therapeutics that target cannabinoid receptors, without the side effect of memory loss.
Cannabinoids are chemicals present in marijuana, as well as synthetic forms of the drug. According to the National Institute on Drug Abuse (NIDA), there are more than 100 cannabinoids in marijuana, including the main psychoactive compound delta-9-tetrahydrocannabinol (THC). These cannabinoids are similar in structure to cannabinoids that occur in the body naturally, such as anandamide. Naturally occurring cannabinoids function as neurotransmitters; they send signals between nerve cells, or neurons, affecting various brain regions, including those responsible for emotion, movement, coordination, sensory perception, and memory and thinking. Because THC and other cannabinoids present in marijuana and synthetic forms are similar to naturally occurring cannabinoids, they are able to bind to cannabinoid receptors situated on neurons and activate certain brain regions.
American Heart Association Meeting Report - Poster: S4054 - Session: HF.APS.P14 American Heart Association
NEW ORLEANS, Nov. 13, 2016 -- Active marijuana use may double the risk of stress cardiomyopathy, an uncommon heart muscle malfunction that can mimic heart attack symptoms, according to research presented at the American Heart Association's Scientific Sessions 2016.
The researchers found that marijuana users were almost twice as likely to develop stress cardiomyopathy compared to non-users, even after taking other cardiovascular risk factors into consideration. Active marijuana use was identified either by information provided by the patient in their medical history, or by a marker in the patient's urine.
"The effects of marijuana, especially on the cardiovascular system, are not well known yet. With its increasing availability and legalization in some states, people need to know that marijuana may be harmful to the heart and blood vessels in some people," said Amitoj Singh, M.D. study co-author and chief cardiology fellow at St. Luke's University Health Network in Bethlehem, Pennsylvania.
Stress cardiomyopathy is a sudden, usually temporary, weakening of the heart muscle that reduces the heart's ability to pump, leading to chest pain, shortness of breath, dizziness and sometimes fainting.
Data from the Nationwide Inpatient Sample identified 33,343 people who were hospitalized with stress cardiomyopathy between 2003-2011 in the United States. Of those, 210 (less than one percent) were also identified as marijuana users. Compared with non-users, researchers found that marijuana users were more likely to be younger, male with fewer cardiovascular risk factors, including less high blood pressure, diabetes and high cholesterol.
However, despite being younger and with fewer cardiovascular risk factors than non-users, during stress cardiomyopathy the marijuana users were significantly more likely to go into cardiac arrest (2.4 percent vs. 0.8 percent) and to require an implanted defibrillator to detect and correct dangerously abnormal heart rhythms (2.4 percent vs. 0.6 percent).
"This development of stress cardiomyopathy in younger patients who used marijuana suggests a possible link that needs to be further investigated," said Sahil Agrawal, M.D., co-author of the paper and also a chief cardiology fellow at St. Luke's.
Marijuana users were more likely than non-users to have a history of depression (32.9 percent vs. 14.5 percent), psychosis (11.9 percent vs. 3.8 percent), anxiety disorder (28.4 percent vs. 16.2 percent), alcoholism (13.3 percent vs. 2.8 percent), tobacco use (73.3 percent vs. 28.6 percent) and multiple substance abuse (11.4 percent vs. 0.3 percent). Because some of these can increase the risk of stress cardiomyopathy, the researchers adjusted for known risk factors to investigate the association between marijuana use and stress cardiomyopathy.
"If you are using marijuana and develop symptoms such as chest pain and shortness of breath, you should be evaluated by a healthcare provider to make sure you aren't having stress cardiomyopathy or another heart problem," Singh said.
The study has some limitations. Because this was a retrospective study, the researchers could not determine how frequently the marijuana users were using marijuana, or what the timeframe was between the use of marijuana and occurrence of stress cardiomyopathy. Observational studies are not designed to prove cause and effect; therefore, it cannot be said that marijuana is or is not a direct cause of stress cardiomyopathy. In addition, because the database the researchers used reports regional but not state-by-state statistics, the researchers could not analyze whether possibly marijuana-related heart problems are increasing where use is legal.
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Co-authors are Mark Fegley, M.D.; Yugandhar Manda, M.D.; Sudip Nanda, M.D.; and Jamshid Shirani, M.D. Author disclosures are on the abstract.
This study did not receive outside funding.
Note: Scientific presentation is at 2 p.m. CT, Sunday, Nov. 13 in the Science and Technology Hall, Clinical Science Section.
Additional Resources: AHA expert perspective audio/photo wmv interview clips (for download/edit) and images related to this release are located on the right column of the release link
HD video clips with researchers/authors of the studies will be added to the release link after embargo.
For more news at AHA Scientific Sessions 2016, follow us on Twitter @HeartNews #AHA16.
Statements and conclusions of study authors that are presented at American Heart Association scientific meetings are solely those of the study authors and do not necessarily reflect association policy or position. The association makes no representation or warranty as to their accuracy or reliability. The association receives funding primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific association programs and events. The association has strict policies to prevent these relationships from influencing the science content. Revenues from pharmaceutical and device corporations are available at http://www.heart.org/corporatefunding.
A highly-publicized study finding that marijuana use is linked to a severe drop in IQ has been successfully defended by the scientific community overseas and in the United States, including the National Institute on Drug Abuse Director Dr. Nora Volkow.
The original study, published last August in the Proceedings of the National Academy of Sciences by Dr. Madeline Meier of Duke University, and colleagues, was the strongest evidence yet that teen use of cannabis could cause a drop in IQ. Opponents of the study claimed that socio-economic factors are to blame.
Around 1000 people all born in the same year in the New Zealand city of Dunedin were interviewed at ages 18, 21, 26, 32 and 38 about their marijuana use. The participants were also tested for their cognitive abilities at age 13 before starting to use cannabis, and at age 38. The study found persistent cannabis use during teenage years was associated with a drop in IQ of seven or eight points by the age of 38.
A new paper contesting the interpretation of the large-scale marijuana study was published in the Proceedings of the National Academy of Sciences by Norwegian Dr. Ole Rogeberg of the Ragnar Frisch Centre for Economic Research in criticizes Meier for failing to control their study for socio-economic status: Poorer kids were getting an initial boost in IQ when they first went to school but that this declined once they left school.
“Indeed, when discussing traits like IQ, it would be surprising for one factor to be 100 percent causal. The strengths of the Meier et al study are that it is longitudinal in nature and that it controlled for a/ /number of factors including years of education, schizophrenia, and other substance abuse. That said, observational studies in humans cannot account for all potentially confounding variables. In contrast, animal studies—though limited in their application to the complex human brain—can more definitively assess the relationship between drug exposure and various outcomes. They have shown that exposure to cannabinoids during adolescent development can cause long-lasting changes in the brain’s reward system as well as the hippocampus, a brain area critical for learning and memory,” Dr. Volkow wrote on NIDA’s website.
“The message inherent in these and in multiple supporting studies is clear. Regular marijuana use in adolescence is known to be part of a cluster of behaviours that can produce enduring detrimental effects and alter the trajectory of a young person’s life—thwarting his or her potential. Beyond potentially lowering IQ, teen marijuana use is linked to school dropout, other drug use, mental health problems, etc. Given the current number of regular marijuana users (about 1 in 15 high school seniors) and the possibility of this number increasing with marijuana legalization, we cannot afford to divert our focus from the central point: regular marijuana use stands to jeopardize a young person’s chances of success—in school and in life,” she concluded.
By CBS News Staff (CBS/AP) Teens who smoke marijuana frequently are more likely to experience a long-term drop in their IQ, according to a new study.
That could be a potential pitfall for millions of teens, given recent estimates show about one in 10 teens in grades nine through 12 smoke marijuana at least 20 times per month. The researchers however didn't find the same IQ dip for people who became frequent users of pot after 18, suggesting pot use is especially dangerous for the developing brain.
"Parents should understand that their adolescents are particularly vulnerable,'" said lead researcher Madeline Meier, a postdoctoral researcher at Duke University's Center for Child and Family Policy.More than 1,000 study participants from New Zealand were tested for IQ at age 13 - likely before any significant marijuana use - and again at age 38. All were born in the town of Dunedin during a year-long span ending in 1973…"Marijuana is very dangerous drug to the brain, particularly in adolescence, and it's also a carcinogen, so it's not healthy for adults either," Dr. Harris Stratyner, vice president of Caron Treatment Centers' New York Clinical Regional Services, told HealthDay. "It's much more dangerous than we've ever given it credit for."
Fran Lowry October 20, 2016 Legalizing medical marijuana may have an adverse effect on educational attainment, new research shows.
A study examining the impact of laws that legalize marijuana on educational attainment shows that states with these laws had an increase in the high-school dropout rate among 12th graders. In addition, among those who did graduate from high school, fewer went on to attend college or to graduate from college.
The study was published online October 11 in Drug and Alcohol Dependence.
Direct Link "More than anything, what we have done is provided good, solid evidence that there is a direct link between marijuana policies and education," lead author Andrew Plunk, PhD, from Eastern Virginia Medical School, Norfolk, told Medscape Medical News.
"With these policy changes, we need to be mindful about how young people might view marijuana. As it becomes approved for medical indications, are kids going to be viewing it as less risky?" Dr Plunk said.
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