The lead article in the most recent issue of Journal of Traumatic Stress (27:2, 2014) presents a small randomized control trial pitting yoga interventions (12 sessions) against “assessment control” (i.e. assessment plus no treatment). The authors suggest this is the first randomized control trial for yoga interventions, something needed since there is significant anecdotal and quasi-research evidence that yoga reduces trauma symptoms. It is purported to work for several reasons: improved breath-control, improved mind-body awareness/mindfulness, and improved stress resiliency.
What did they find?
The answer to the title question: yes, but not more than controls. Some improvement is noted in the Yoga intervention group: reduction of re-experiencing symptoms and reduction of hyperarousal symptoms. However, the same reductions are also noted in the assessment control group. You might wonder why. The authors suggest that the control group found benefit in tracking their symptoms each week. Thus, self-monitoring may help improve well-being, especially if the person also is accepting and normalizing symptom expression of PTSD. Thus, both groups may have received the same intervention: self-awareness, self-monitoring, and self-acceptance.
Now, this trial was rather small, just 38 in total. With a larger study, researchers might find more power to their intervention. Why keep trying? Yoga is (a) low-cost, (b) not particularly taxing from an emotional standpoint (thus few drop-outs when compared to something like Prolonged Exposure), and (c) something that helps sufferers stay attuned to their body.