Evaluation of therapeutic efficacy and mechanistic basis of yoga in the management of adverse respiratory health and neuropsychological deficits in pesticide exposed Indian farmers

Abstract

BACKGROUND The respiratory function and neuropsychological deficits remain major health concerns in chronically pesticide-exposed farmers across the globe. However, there is a scarcity of studies that address the clinical management of these adverse health outcomes of occupational pesticide exposure to farming populations by administering a Yoga-based intervention, which has the potential to improve thoracic compliance and lung function. AIM AND OBJECTIVES We aimed to investigate whether Yoga-based intervention could mitigate the effects of chronic exposure to pesticides on respiratory and cognitive functions. Secondarily we also aimed to test if oxidative stress reduction could underlie the intervention's impact on the health outcomes, health-related quality of life (HRQOL), and oxidative stress markers in farmers chronically exposed to pesticides. METHODS In the present study, we report the findings of parallel two-armed randomized clinical, blinded outcome assessors that tested the efficacy of a yoga-based intervention on pulmonary and cognitive functions in pesticide exposed male farmers. Farmers were screened on their self reported history of at least six months of spraying operations in the field. Of 634 farmers screened across five villages, 140 male farmers (mean [SD] age, 38.75 [7.50] years) with mean pesticide exposure of 5.71 years (SD 3.04) were included and randomized to yoga (n = 70), or waitlist control arm (n = 70). Yoga intervention was delivered in 60-minute groups for 12 weeks. vi A total of 123 participants completed the post-intervention assessment. Analysis was by intention-to-treat. The intervention was unblinded, but the outcome assessment blinded the treatment assignment. The primary outcome was a change in pulmonary function parameters (percent predicted value of FVC, FEV1, %FEV1/FVC, PEFR, and FEF 25–75%) after 24 weeks of intervention. Secondary variables were assessed using neuropsychological assessment TMT (Trail making test), DSST (Digit symbol substitution test), WHO Quality of life-BREF, and Perceived stress scale. We present an application of the causal inference approach to mediation analysis. Linear regression was used to analyze study outcomes as adjusted mean differences (AMDs), additionally adjusted for their comparable value at baseline. Mediation analysis was also done considering oxidative stress markers as potential mediators. This study is registered with ClinicalTrials.gov, number CTRI/2019/11/021989. RESULTS At the end of 6 months of intervention, the overall follow-up in the participants was 87.85% (n=123); 90% (n=63) in the control group, and 85.71% in the yoga group (n=60). The mean age of the study cohort (n=140) was 38.75 (SD =7.50) years. Compared with the control group, at 24 weeks post-intervention, the breathing focused Yoga group had significantly improved the markers of airway obstruction, after adjusting for confounders, FEV1, FVC, FEF25-75 [z score adjusted mean differences (95% CI); 1.66 (1.10-2.21), respectively. A fraction of FEF25- 75 change (mediation percentage 23.95%) was explained by glutathione augmentation. There were also significant improvements in cognitive scores of DSST, TMT-A and TMT-B, and WHOQOL-Bref. vii CONCLUSION In this 24-weeks randomized controlled trial on chronically pesticide exposed farmers, breathing focused yoga intervention was significantly more effective than the wait-list control group in the alleviation of spirometry-based indices of airflow limitation and cognitive decline. A significant mediating effect of glutathione augmentation was also observed concerning the effect of the intervention on FEF25-75%. These findings provide an important piece of beneficial evidence of the breathing-based yoga intervention that needs validation across different farming ethnicities. Trial Registration Clinical Trial Registration Number: CTRI/2019/11/021989 Keywords: Farmers, Pesticide exposure, Breathing-focussed Yoga Intervention, Respiratory Decline, Cognitive Decline