Correlations between negative symptoms, physical activity and metabolic syndrome in patients with schizophrenia – a literature review

In schizophrenia patients, metabolic syndrome occurs more often than in the general population, causing increased morbidity and mortality. In this paper, we review data concerning potential causes of metabolic syndrome. The purpose of this study is to highlight various arguments in the discussion about metabolic syndrome in patients with schizophrenia. The importance of the negative symptoms and physical activity as factors which have a significant impact on development of metabolic syndrome components is especially underlined. The scientific reports referring to already studied correlations between metabolic syndrome, its particular criteria (according to the National Cholesterol Education Program Adult Treatment Panel III) and its probable causes are presented. The potential role of antipsychotic medications and the pathogenesis of metabolic abnormalities in antipsychotic-naive first-episode schizophrenia patients are also discussed. Those issues are frequently mentioned in the debate about the explored phenomena. In previous studies, cross-sectional methodology has been applied and the authors used subjective tools, such as scales and questionnaires, to assess physical activity, which may raise doubts as to the value of such measurements. Results which have been published so far are contradictory and are not sufficient to create consistent guidelines of clinical management of metabolic syndrome in patients with schizophrenia. For better understanding of potential relationships, further multicenter research using objective methods of evaluating physical activity, such as accelerometry, is required. That might contribute to implementing therapeutic programs to decrease mortality among schizophrenia patients.