REVIEW OF: Bryant RA et al, Lancet Psychiatry 2023;10(1):21–29

STUDY TYPE: Single-blind, randomized controlled trial

Exposure therapy, a staple PTSD treatment, works through extinction learning. This involves repeated, safe exposure to trauma-related cues, which gradually reduces their perceived threat. For example, someone who developed a fear of driving after a car accident might start by simply sitting in a parked car, then try driving a short distance. However, not everyone benefits from this approach, and up to half don't respond at all. This led researchers to ask if exercise—which may enhance learning by raising ­brain-derived neurotrophic factor (BDNF)—could augment exposure therapy.

The study recruited 130 participants with PTSD, most of whom (61%) were women. About one-third were prescribed antidepressants. All were younger than 70 years, with a low suicide risk and no psychosis, substance dependence, or brain injuries or physical disorders that could interfere with exercise. About 50% of subjects’ trauma was classified as assault, close to 30% as road accidents, and the rest as other accidents. Participants were equally and randomly assigned to exposure therapy with passive stretching or exposure therapy with vigorous aerobic exercise. Ten minutes of exercise was performed after each of nine 90-minute weekly therapy sessions and supervised by the therapist, who motivated participants to maintain their heart rate between 65% and 85% of their maximum (220 beats per minute minus age in years) as measured by chest and wrist monitors.

After six months, both groups improved; however, the therapy + exercise group had a 12.1-point drop in symptoms (95% confidence interval: 2.4–21.8) on a blinded clinician-administered PTSD scale (Clinician Administered PTSD Scale-2) compared to controls. This correlated with a moderate but meaningful effect size of 0.6. The exercise group also saw a more pronounced improvement in depression symptoms per the Beck Depression Inventory-II scale. There were no notable differences between groups in anxiety, alcohol use, or maladaptive appraisals, which might be influenced by factors independent of the therapy.

Effects immediately after the nine-week interventions were not evident, and the study could not conclude the observed improvements were due to BDNF. Nevertheless, these findings suggest that exercise may enhance long-term learning from exposure therapy. Some limitations of the study include most participants being White women, all participants being less than 70 years old, and the relatively strict inclusion criteria.

CARLAT TAKE

Recommending exercise to patients is almost always a good idea. In this study, just 10 minutes of aerobic exercise after each session of exposure therapy led to better outcomes for PTSD.