Concussion and depressive symptoms in high school students: impact of physical activity and substance use.

Objective: To investigate the association between concussion history and depressive symptoms after adjusting for physical activity, substance use, and illicit drug use.

Methods: We analysed data from the Adolescent Behaviour and Experiences Survey, a nationally representative survey of adolescents in the USA. Our independent variables were history of concussion in the 12 months preceding survey completion; self-reported weekly physical activity (days per week with >60 min of physical activity, 0-7 scale); substance use over the past 30 days (yes vs no) and illicit drug use throughout lifetime (yes vs no). Our dependent variable was participant-reported sadness/hopelessness over the past 12 months (yes vs no).

Results: Among 7499 adolescents (9th-12th grade, 50.4% female), reporting one or more concussions over the past year was not associated with the odds of depressive symptoms (OR: 1.13, 95% CI: 0.93 to 1.37, p=0.21). Each additional day of physical activity per week was associated with a lower odds of depressive symptoms (OR: 0.91; 95% CI: 0.89 to 0.94; p<0.0001). Illicit drug use (OR ever vs never: 2.48; 95% CI: 1.96 to 3.13; p<0.0001) and substance use (OR yes vs no: 2.77; 95% CI: 2.34 to 3.29; p<0.001) were associated with a higher odds of depressive symptoms.

Conclusions: Adjusting for physical activity, substance use and illicit drug use, concussion was not significantly associated with depressive symptoms. This novel discovery informs clinicians as they counsel adolescents with concussion; future research should examine physical activity and avoidance of substance/illicit drug use as postinjury recommendations in an effort to lower the risk of depressive symptoms.