Group processes and physiological health in group-based interventions: A systematic review

Social identity-related group processes are increasingly recognized as influencing psychological and physical health, yet their impact on stress-related biomarkers remains unclear. We conducted a systematic review and meta-analysis of group-based interventions examining physiological markers linked to stress and long term health. From 1606 records, 14 studies met inclusion criteria. While interventions did not consistently improve biomarkers compared to controls, reductions in blood pressure, increased heart rate variability, and lower salivary cortisol were observed when key group processes (social support, cohesion, working alliance, and social norms) were effectively mobilized. Positive group processes were associated with more adaptive physiological functioning (r = −0.19), where lower scores reflected healthier response profiles (e.g. lower blood pressure). This review provides novel insights into how social identity processes operate in group-based interventions and their potential for shaping physiological health. We highlight the importance of designing interventions that actively foster supportive and cohesive group environments