Psychological and endocannabinoid responses to aerobic exercise in substance use disorder patients

Exercise has been examined as an adjunctive treatment for substance use disorders (SUDs), yet few exercise interventions have been conducted among patients undergoing intensive outpatient (IOP) treatment, who may be the most vulnerable to relapse and for whom exercise could provide the most benefits. This study examined the effects of aerobic exercise, in addition to IOP treatment, on psychological variables and endocannabinoids in individuals with SUDs. Methods: Twenty-one SUD patients (mean age 35 years) were recruited from local IOPs. Participants were randomized to either treatment-as-usual (TAU, at their outpatient clinic) or TAU plus aerobic exercise training (EX). EX participants engaged in supervised, moderate-intensity exercise for 30 min, 3 times/week for 6 weeks. TAU participants came into the laboratory once per week for assessments and a 30-min quiet rest session. Participants provided blood samples and completed questionnaires evaluating substance use, mood states, depression, anxiety, perceived stress, self-efficacy to abstain from substance use, and craving. Data were analyzed with Mann-Whitney U tests or mixed model ANOVAs to determine group differences in outcomes acutely and over 6 weeks. Results: Over 6 weeks, there were reductions in perceived stress (p < 0.01) and craving (p < 0.05) for both groups. There were no group differences in abstinence rates or changes from baseline in self-efficacy, depression, or anxiety (p > 0.05). Acutely, both exercise and quiet rest sessions led to reductions in craving, tension, depression, anger, confusion, and total mood disturbance (all ps < 0.05). In addition, the EX group experienced acute increases in vigor and circulating concentrations of the endocannabinoid, anandamide (p < 0.01). Conclusions: An adjunctive aerobic exercise program during SUD treatment was associated with similar reductions in perceived stress and drug craving as standard care. Thirty minutes of exercise or quiet rest led to acute improvements in mood, but exercise produced the additional benefit of increases in vigor and circulating anandamide.