#26 - - Network meta-analysis on psychological interventions efficacy on immune biomarkers

Background Altered immune-inflammatory status is frequent in individuals with mental disorders or exposed to chronic stress, yet the efficacy of psychological interventions in ameliorating immune system function remains controversial. Methods This was a systematic review and frequentist random-effects network meta-analysis of randomised controlled trials (RCTs) assessing the effects of psychological interventions, against a control condition, on biomarkers of innate and adaptive immunity in adults. PubMed, Scopus, PsycInfo, and Web of Science were searched up to Oct 2022. Cohen's d at 95% confidence interval (CI) was calculated to assess the effect sizes of each class of intervention against active control conditions at post-treatment. The study was registered in PROSPERO (CRD42022325508). Results Of the 5024 articles retrieved, we included 104 RCTs (n=7820 participants) and 13 types of clinical interventions. Compared with the control conditions, cognitive therapy (d=−0.95, 95% CI: −1.64 to −0.27), lifestyle (d=−0.51, 95% CI: −0.99 to −0.02), and mindfulness-based (d=−0.38, 95% CI: −0.66 to −0.09) interventions were associated with post-treatment reduction of proinflammatory cytokines and markers. Mindfulness-based interventions were significantly associated with post-treatment increase in anti-inflammatory cytokines (d=0.69, 95% CI: 0.09 to 1.30). Cognitive therapy was associated also with post-treatment increase in white blood cell count (d=1.89, 95% CI: 0.05 to 3.74). Certainty of evidence (GRADE approach) was low-to- moderate. Conclusion This meta-analysis provides evidence for psychological interventions, and particularly mindfulness, in improving immune system function. Results should be considered when implementing clinical psychological interventions in populations with or at risk of inflammation- related conditions or altered immune function.