A meta-analysis published in JAMA Psychiatry suggests that Metacognitive training (MCT) was useful in reducing positive and negative symptoms of schizophrenia.

This analysis included 43 studies (46 reports) including participants with schizophrenia and related psychotic disorders. 40 reports were generated in the meta-analysis (N=1816 participants) and 6 reports were included in the narrative review. 

The results of the analysis showed that , MCT was linked to positive symptoms (g = 0.50; 95 percent CI, 0.34-0.67), delusions (g = 0.69; 95 per cent CI, 0.45-0.93), hallucinations (g = 0.26; 95 per cent CI, 0.11-0.40), cognitive biases (g = 0.16; 95 percent CI, 0.03-0.29), self-esteem (g = 0.17; 95 percent CI, 0.03-0.31), negative symptoms (g = 0.23; 95% CI, 0.10-0.37), and functioning (g = 0.41; 95% CI, 0.12-0.69).  These connections were kept for up to a year. The well-being and the quality of life effect size was measured in only one study and found to be non-significant (g = 0.20; 95 percent CI, 0.07 to 0.47).The year of publication was linked to moderated hallucinations (= 0.04; 95 percent confidence interval, 0.00-0.07). 

MCT appears to be a beneficial and enduring low-threshold intervention that may be flexibly administered at low cost to patients with psychotic illnesses and MCT use may be included in the guidelines for schizophrenia treatment. (Medscape Medical News, April 06, 2022); JAMA Psychiatry. Published online March 23, 2022. doi:10.1001/jamapsychiatry.2022.0277