It is well-known that a sedentary lifestyle heightens risk for a variety of chronic medical problems, including obesity, diabetes, and hypertension. This is especially concerning for adolescents, because most of their routine daily activities—such as sitting in class, doing homework, riding in motorized transportation to and from school, interacting on social media, and watching entertainment—require little physical effort. Often co-occurring with sedentary lifestyle, emotional disturbances and substance use increase the likelihood of social maladjustment and subsequent development of mental health disturbances and addiction in adulthood. Notably, participation in physical activities declines during adolescence around the same point when substance use usually begins.
The prevalence of marijuana use is high and increasing, and it presents a mounting public health problem. Habitual consumption of marijuana portends the same medical disorders as can result from a sedentary lifestyle, often leading to amotivational syndrome, a generalized diminution of aspiration for achievement. Concurrent with these effects of cannabis, the prevalence of physical inactivity is increasing over time, and effortful expenditure of energy such as participation in sports decreases between childhood and adulthood. In aggregate, these findings suggest that low physical activity may increase risk for developing cannabis use disorder.
Accordingly, this longitudinal studyopens in new window of participants spanning the ages 12–22 years examined the correspondence between change in physical activity and frequency of substance use on risk for developing cannabis use disorder.
The Center for Education and Drug Abuse Research at the University of Pittsburgh prospectively tracked a sample of boys and girls drawn from over 700 families. The Drug Use Screening Inventory (DUSI) was administered to the participants at 12–14, 16, 19, and 22 years of age. This self-administered internet-based assessment, with parallel versions for youths and adults, takes about 15 minutes to complete and asks participants to report substance use frequency in relation to mental health, family, social, vocational, psychological, academic, and health problems. So that intervention targets may be identified and prioritized, the participant’s severity of problems in over 24 measurement domains is automatically quantified from 0% to 100%. Responses to items from the DUSI’s Leisure and Recreations Scale and overall consumption frequency index, which encompasses 20 types of substances, documented the strength of correspondence between physical inactivity and substance use frequency leading to cannabis use disorder.
We evaluated two hypotheses:
Hypothesis 1: The magnitude of risk for cannabis use disorder results conjointly from the rate (or slope) of decline in physical activity concomitant with the rate of increase in substance use frequency from childhood to young adulthood.
Hypothesis 2: The rate of decline in physical activity throughout adolescence is predicted by the number of biological parents with substance use disorder.
Hypothesis 1 was confirmed by the finding that the slope of decline in physical activity throughout adolescence correlates with substance use frequency and predicts cannabis use disorder. Hypothesis 2 was confirmed by observing that the number of biological parents with diagnosed substance use disorder predicts their child’s rate of decline of physical activity. In addition, the study showed that physical inactivity was a mediator of the association between parental substance use disorder and the child’s risk for cannabis use disorder. This finding shows that physical inactivity is an important aspect of the risk for cannabis use disorder.
These results point to the preventive benefits of encouraging a physically active lifestyle in children and adolescents who are at high risk for substance use disorder. Screening assessments can be routinely and expeditiously conducted to detect at-risk youths and thereby guide the allocation of resources needed to prevent addiction in the most vulnerable children and adolescents.
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