Adolescents who use or have used cannabis are much less likely to engage in adequate levels of physical activity, according to a study published in Drug and Alcohol Dependence.
The vast majority of adolescents around the world do not meet the 60 minutes a day of moderate-vigorous physical activity that is recommended by the World Health Organization (WHO). This study reveals that cannabis use, which is associated with increased apathy and decreased motivation, could be a contributing factor.
Previous research has found an association between low physical activity levels and the use of marijuana. However, little is known about how cannabis use affects motivation to exercise and no studies have explored populations outside the USA. Researchers were particularly interested in studying low and middle income countries where the use of cannabis seems to be increasing rapidly.
Researchers analyzed data from the Global school-based student health survey which had students between the ages of 12-15 complete questionnaires. The survey was developed by the WHO and the US Centers for Disease Control and Prevention and was designed to measure risk and protective factors associated with major diseases.
The study involved 89,777 students from 21 countries. The countries were classified as either low-income, lower middle-income, or upper middle-income. To assess cannabis use, researchers used the question, “During the past 30 days (or during your life), how many times have you used marijuana?” To assess physical activity, students were questioned on their activity levels in the past week. In line with WHO recommendations, students reporting at least 60 minutes of physical activity a day for the last 7 days were considered to meet adequate exercise levels.
Results showed that adolescents who used marijuana either currently or in the past were much less likely to meet adequate levels of physical activity than those who had never used marijuana. Specifically, 17.3% of those who never consumed cannabis met physical activity recommendations. By contrast, only 7.3% of those who used cannabis in the past and only 6.9% of those who were using it currently were getting enough physical activity.
Researchers propose several mechanisms that may be involved. One explanation is that the use of marijuana is related to heightened feelings of lethargy and physical effort, which might make users less likely to take on physical exercise. Another is that prolonged marijuana use has been linked to dopaminergic down-regulation, which may be associated with reduced reward sensitivity and therefore lack of motivation.
Even if cannabis use is not causing low levels of physical activity, the fact that they are co-occurring together is of concern. Researchers point out that lack of exercise leads to numerous health consequences, including suicidal ideation and mortality. Marijuana use has also been linked to these negative outcomes, so pairing both habits together may be particularly damaging for youth. Researchers explain, “cannabis use in adolescents who are physically inactive may further compound future health risks.”
Researchers stress the need for additional research to determine how best to support adolescents using cannabis. They say, “This may not only help prevent long-term cannabis use and its reported adverse events but also have a positive impact on other behaviors such as physical activity, smoking and alcohol use”.
The study, “Cannabis use and physical activity among 89,777 adolescents aged 12-15 years from 21 low- and middle-income countries”, was authored by Garcia Ashdown-Franks, Catherine M. Sabiston, Davy Vancampfort, Lee Smith, Joseph Firth, Marco Solmi, Nicola Veronese, Brendon Stubbs, and Ai Koyanagi.
