Objectives: The aim of this paper is to review results of studies on the effectiveness of metacognitive training (MCT) for patients with schizophrenia in reduction of psychotic symptoms and cognitive biases. Furthermore, other variables, like social functioning, insight and neurocognitive functions, are analyzed.
Methods: Systematic search in databases PubMed, EBSCO, Google Scholar, EMBASE, Cochrane Central Register of Controlled Trials and PsycINFO regarding studies on the effectiveness of the MCT was made. The review included 14 studies published in years 2009-2015, in which design of the study made comparison between MCT group and control group possible.
Results: Combined number of patients in MCT group was 354 and 355 in control group. The largest effect size was obtained for severity of delusions (d < 0.23; 1 >), especially reduction of conviction and distress of delusional beliefs. An effect size regarding negative symptoms reduction was small. Large effect size was observed for insight improvement (d < 0.45; 1.32 >). Positive impact of MCT on cognitive biases severity (d < 0.21; 0.83 >, especially jumping to conclusions) and improvement in some aspects of neurocognitive functions was observed (d < 0.2; 0.63 >). There was no improvement in social functioning of patients in MCT group. Follow-up studies show sustainability in symptoms improvement lasting at least 6 months.
Conclusions: MCT is an effective form of therapy in reduction of delusions, cognitive biases related to schizophrenia and improvement of insight. Relatively easy accessibility and sustainability of therapeutic effects indicates that MCT can by effectively used in therapy of schizophrenia. To enhance training efficacy, especially in patients' general functioning, combining it with others forms of therapy is to be considered.
Keywords: cognitive biases; group metacognitive training; schizophrenia.