Few barriers
The researchers found no significant differences in PTSD severity, as measured by CAPS-2 score, between treatment groups at 10 weeks – that is, immediately post treatment (mean difference, 7.0; 95% confidence interval, –2.3 to 16.4; P = .14).
However, significantly greater reductions in PTSD severity were found in the aerobic versus the stretching group at 6-month follow-up (mean difference, 12.1;95% CI, 2.4-21.8; P = .023), pointing to a “moderate effect size” (d = 0.6; 95% CI, 0.1-1.1]).
Although there were no differences found at 6-month assessment between rates of PTSD diagnosis (25% of the aerobic vs 27% of the stretching group), more participants in the aerobic group reached a “minimal clinically important difference,” compared to those in the stretching group (96% vs. 84%, respectively, x2 = 4.4; P = .036).
There were also superior benefits found in the aerobic versus the stretching group on depression severity at 6 months (a secondary outcome), with a mean difference in Beck Depression Inventory-2 score of 5.7 (95% CI, 0.5-10.9; P = .022), yielding a “moderate effect size” (d = 0.5; 95% CI, 0.1-1.0]).
There were no adverse events associated with the intervention, and almost all the sessions (88%) complied with the treatment protocol.
The researchers noted several limitations. For example, they did not obtain plasma to measure BDNF concentrations, so they could not “infer whether the mechanism of change involved BDNF.”
In addition, they did not perform sex-specific analyses. “Future studies could increase the sample size to investigate sex differences because females display less BDNF change following exercise than do males,” they wrote.
Nevertheless, the study “provides initial evidence of a simple and accessible strategy that clinicians could readily apply in combination with exposure therapy,” they stated. “Whereas many pharmacologic interventions pose barriers, including cost, requirement for prescriptions, and patient resistance to drugs, exercise offers clinicians a strategy that can be implemented with few barriers.”
Dr. Bryant emphasized that one study “does not represent a body of evidence, and so it is essential that this finding be replicated in other trials before it can be recommended for clinical use.” He noted that other trials are “currently underway.”
Easy augmentation
In a comment, Barbara Rothbaum, PhD, professor in psychiatry and director of the Trauma and Anxiety Recovery Program at Emory University, Atlanta, called it a “well-controlled trial augmenting exposure therapy for PTSD with brief aerobic exercise and finding some benefits of the augmented condition at 6 months posttreatment but not immediately posttreatment.”
The study’s methodology – that is, using independent standard assessment of PTSD and rating audio recordings of therapy sessions for treatment fidelity and quality – can lead us to “be confident in their [the researchers’] conclusions,” she said.
Dr. Rothbaum, who was not associated with this study, described research into methods to augment exposure therapy for PTSD as “timely and clinically relevant.”
Exercise “would be an easy augmentation for many clinicians if it is helpful,” she noted.
The study was funded by the Australian National Health and Medical Research Council. The authors and Dr. Rothbaum reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.