Psychosocial interventions have recently emerged as a potentially useful strategy for addressing inflammation-related diseases, but the types of psychosocial interventions that can improve the immune system functionality are unknown. The objective of this study is to determine the associations between 8 different psychosocial interventions and 7 markers of immune system function.

This is a systematic review and meta-analysis of randomized clinical trials (RCTs) of Scopus, PsycInfo, ClinicalTrials.gov, and PubMed. 56 RCTs, including 4,060 participants, were used to carry forward the analysis, which included 8 psychosocial interventions, 7 immune outcomes, and 9 moderating factors. The primary outcomes of the analysis were the pretest-posttest-control (PPC) group effect sizes (PPC G) for the 7 immunologic outcomes.

When randomly assigned to a psychosocial intervention condition or a control condition, the participants who received the psychosocial intervention showed a 14.7% improvement in beneficial immune system function and an 18.0% decrease in harmful immune system function. These associations were persistent for at least 6 months following treatment and were significant across all age groups, sexes, and intervention durations. Cognitive behavior therapy (CBT) resulted in the most reliable association, followed by combination interventions. 

The research concluded that psychosocial interventions are positively associated with improved immune system functionality and may be used as a strategy to improve immunity in populations.

Ref: https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2766707?resultClick=1