Peripheric metabolic abnormalities in schizophrenia patients

Introduction Schizophrenia (SCZ) is frequently associated with metabolic symptoms including dyslipidaemia, hyperinsulinemia, type 2 diabetes and obesity. In fact, SCZ patients have been reported to present higher prevalence of these conditions than general population, commonly associated to second generation antipsychotic therapy. Recent studies, however, have demonstrated that peripheral metabolic disturbances can appear at disease onset or drug-naive patients. Objectives/aims To assess metabolic disturbances in first episode and/or drug-naive SCZ patients. Methods We conducted a literature review through Pubmed search for MeSH: schizophrenia, metabolism, glucose, insulin. Controlled studies on first episode and/or drug-naive SCZ patients were included. Results Several studies showed no change in SCZ patients’ fasting blood glucose, while others found increased glucose levels and impaired glucose tolerance in SCZ patients compared to healthy controls in several recent studies. Hyperinsulinemia and insulin resistance have also been identified in antipsychotic-naive SCZ patients and it has been suggested that early onset patients are more likely to present insulin resistance. In addition, there's evidence of increased circulating levels of chromogranin A, pancreatic polypeptide, prolactin, cortisol, progesterone, thus emphasising that multiple components of the hypothalamic-pituitary-adrenal-gonadal axis may be affected in SCZ. These elevations were associated to normal glycaemia suggesting there may be insulin intolerance during early stages of SCZ, requiring an increased secretion from pancreatic Bcells to maintain normal glucose levels. Conclusions Recent studies of first onset and/or drug-free schizophrenia patients have shown impaired fasting glucose tolerance, hyperinsulinemia and insulin intolerance, suggesting that metabolic abnormalities may play a role in SCZ onset and pathophysiology.