Question: How consistently are psychosocial interventions associated with changes in immune system function, and which immunologic, demographic, or clinical factors moderate these associations?

Findings: In this systematic review and meta-analysis of 56 unique randomized clinical trials and 4060 participants, psychosocial interventions were associated with positive changes in immunity over time, including improvements in beneficial immune system function and decreases in harmful immune function that persisted for at least 6 months following treatment for participants randomly assigned to a psychosocial intervention vs a control group. These associations were most reliable for cognitive behavior therapy and multiple or combined interventions and for studies that assessed proinflammatory cytokines or markers.

Meaning: These findings suggest that psychosocial interventions may enhance immune system function and may thus represent a viable strategy for improving immune-related health.