Discussion
fatigue, pain, depression, reduced pain, cognitive errors
CHRONIC PAIN, SECONDARY
The aim of this study was to examine the long-term efficacy of yoga (vs. CBT) on symptoms of GWI, including pain, walking distance/fatigue, depression, autonomic symptom severity, and quality of life. During the 6-month follow-up period, our results from the BPI-SF showed evidence of reduced pain severity in the yoga group compared to the CBT group, with almost twice as many veterans meeting criteria for clinical improvement in pain severity in the yoga group than the CBT group at 6 months post-intervention (45% vs. 28%). We did not find between-group longitudinal differences in BPI-SF pain interference, BPI-SF total score, walking distance, depression, autonomic symptom severity, or quality of life. However, secondary within-group analyses showed long-term improvements in BPI-SF pain interference, BPI-SF total score, and walking distance in the yoga group but not in the CBT group. Our results failed to demonstrate long-term within-group treatment gains for CBT or yoga on measures of depression, autonomic symptom severity, or quality of life.To our knowledge, this is the first RCT to report long-term benefits of yoga for GWI. A few other types of CIH interventions have shown similar effects. In one such trial, mindfulness-based stress reduction (vs. treatment as usual) was associated with greater reductions in pain, fatigue, depression, and cognitive errors in everyday tasks at 6 months post-intervention [The pattern of results across multiple CIH studies is indicative of multisystemic healing and may be linked to the theoretical underpinnings of yoga and related CIH interventions. A core assumption underlying CIH approaches is the construct of holistic healing, which emphasizes the use of feedback processes between the mind and body to achieve greater homeostatic regulation [In our study, the yoga protocol emphasized the connection between movement and the breath, which may have increased relaxation and resulted in decreased chronic pain and fatigue, both of which are common in multisymptom illnesses [Interestingly, consistent with prior results showing limited efficacy of CBT for GWI [While intriguing, our interpretations must be contextualized within the limitations of the present study. For example, there was greater dropout in the CBT group than in the yoga group. Even with the use of maximum likelihood estimation, the estimates may have been biased by differential attrition. Moreover, the clinically significant improvement and effect size statistics may have been biased by attrition. Due to the small sample size, the three-way interaction in the sensitivity analysis was likely underpowered. Although it revealed greater reductions in BPI-SF total score in the yoga group, as a conservative approach, we did not report this as a meaningful finding. To increase power and rectify common issues related sensitivity analyses, studies with larger sample sizes will be needed [