Teen Use of Marijuana May Lead to Bipolar-Like Symptoms Later on in Life

Marijuana use may help clinicians better identify those vulnerable to bipolar disorder and help them to develop better intervention methods.

While the effects of marijuana use on fully grown adults is still being debated, the impact on teens is becoming clearer. For decades, researchers have been trying to discover if marijuana use has any negative effects on adolescents. This is important because the teen years are when people usually start to experiment with it. One in three high school students use the drug, a recent survey found. 35% of 12th graders ingested cannabis within the past year, while 6% said they use pot daily or nearly so.


Previous research found that chronic use might act as a catalyst for a schizophrenic episode, for those barreling towards one. It can also interfere with brain development in the young. Several studies have found that chronic use from age 16 or before, can alter the development of the prefrontal cortex. This area grows rapidly during adolescence and doesn’t fully mature until one is in their mid-20s.

The prefrontal cortex is responsible for complex reasoning, decision making, social information processing, and judgment. Unfortunately, the team in that study didn’t prove a causal relationship, merely a strong correlation. Although evidence is piling up, there really isn’t an ethical way to perform clinical trials that would provide clear causality.

It’s believed that use of marijuana before age 16 can impact the development of the prefrontal cortex. Credit: Getty Images.

Links between teen marijuana use and schizophrenia, mood disorders, and learning deficits have been investigated in depth. However, a link between bipolar disorder and teen use has received little attention, until now. Once known as manic depression, bipolar is when a person alternates between phases of mania and depression. In this study, researchers found that teens who used marijuana consistently, considered two to three times per week, were far more likely to experience hypomania or bipolar symptoms later in life.   

Researchers from the University of Warwick in the UK conducted the study. They were led by Dr. Steven Marwaha, a clinical psychologist there. He and his team’s findings were published in journal Schizophrenia Bulletin. Researchers specifically zeroed in on hypomania. This is on the manic side of bipolar which includes symptoms such as a lack of sleep, hyperactivity, and feelings of elation or excitement. Such mania can put a serious damper on one’s life.

Dr. Marwaha and colleagues examined the data of 3,370 participants, who were all part of the Avon Longitudinal Study of Parents and Children (ALSPAC). This birth cohort study follows 14,701 children born between April 1, 1991 and December 31, 1992. At age 17, each participant was asked about their marijuana use. Nearly 5% of boys and almost 2% of girls reported such use. While at ages 22-23, each received the Hypomania Checklist Questionnaire (HCL-32). This was a 32 question self-reported assessment evaluating participants on hypomanic behavior.

Until we find an ethical way to study how marijuana effects the teen brain, all of our knowledge on the subject will continue to be correlative rather than causal. Credit: Getty Images.

From the total pool, researchers identified 3,370 ALSPAC participants who showed symptoms of hypomania. Those who reported using marijuana 2-3 times per week at age 17 or before, were far more likely to report hypomania symptoms at 22-23. Any use in the teen years increased risk, and the higher the usage the greater the risk. Marwaha and colleagues adjusted for things like gender, abuse, adversity while young, alcohol and other drug use, and mental health issues such as anxiety or depression by age 18.

Men were more likely to show signs of hypomania, as they were more likely to have used marijuana. Another finding, physical or sexual abuse in childhood was indirectly linked with increased cannabis use and hypomania symptoms. Some experts hypothesize that cannabis may be used to help soothe emotional pain related to trauma, which left undealt with, may lead to a bipolar diagnosis later in life.

Dr. Marwaha said, "Adolescent cannabis use may be an independent risk factor for future hypomania, and the nature of the association suggests a potential causal link. As such it might be a useful target for indicated prevention of hypomania." The study did have limitations. For instance, in some cases, hypomania symptoms preceded cannabis use. Future research will either confirm or deny these results.

The good news is, teen marijuana use and in fact all drug use has seen a downward trend, even as marijuana stigmatization and illegality has soften across the US. A National Institute of Drug Abuse (NIDA) survey last year, found that marijuana use among 8th and 10th graders continued to drop. It’s now at its lowest point in 20 years. While use among 12th graders, it’s remained flat for the past five.

So what does marijuana do to an adult’s brain? Find out here:

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A Cornell study, published in August, has discovered that restaurants that list calorie content help customers moderate the amount of food they consume — albeit, by a little. Still, a little can go a long way once you become accustomed to it.

The research team of John Cawley, Alex Susskind, and Barton Willage set up shop in two restaurants for a randomized field experiment. Two different groups were then told to order: a control group with normal menus and a treatment group, which read from menus featuring calorie information. By the end, 5,500 diners contributed to the study.

The treatment group ended up ordering 3 percent fewer calories than the control group — a result of 45 calories per meal. The biggest effect seems to be on consumer awareness. The researchers noted that customers were surprised by how many calories basic meals, such as a tomato soup/grilled cheese combo, has. They continue,

The findings come at a time when most Americans don't have a precise estimate of how many calories they're eating, because one-third of their food is prepared outside the home. At the same time, the obesity crisis in America has reached epidemic proportions; the prevalence of obesity in adults has nearly tripled in the past 50 years, to nearly 40 percent of the population in 2016.

This follows a law requiring chains with 20 or more locations to post calorie content on menus and menu boards, which went into effect earlier this year. The move was set to launch in 2011 as part of the Affordable Care Act's requirements, yet pushback from lobbying efforts delayed its implementation.

Part of the gripe from restaurant chains (especially pizza establishments) is that it will reduce profits. Yet in the Cornell study researchers found no evidence of monetary loss between the groups. In fact, healthier options often cost more than junk food. That said, patrons realizing which restaurants are not healthy could have a ripple effect. Though the Cornell study is an outlier — other studies have found that the calorie content does not change minds — it might be pushing restaurants to offer more low-calorie options.

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The cost to restaurants does not nearly equate to those on our medical infrastructure. According to the CDC, obesity is costing the U.S. $147 billion each year. This involves direct and indirect medical problems related to being overweight, including cardiovascular disease, type 2 diabetes, immune system-related problems, and many other ailments.

John Cawley, a professor of policy analysis and management in the College of Human Ecology at Cornell, views the calorie listing on menus as an easy to implement solution.

It's a cheap policy to put in place, and the fact that there is a reduction in calories ordered makes it appealing.

While not the only solution, it's a step in the right direction. Awareness is a catalyst for change, and one thing is certain: we can't keep heading blindly in the direction we've been going. The consumption of unhealthy high-calorie foods, beginning with the frozen dinner revolution of post-World War II America right up through pumpkin spice lattes, has made us a sick and diseased nation. Every calorie counts.

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