title: Plasma adiponectin levels in schizophrenia and role of second-generation antipsychotics: a meta-analysis.
abstract: BACKGROUND
  People with schizophrenia are more likely than general population to suffer from metabolic abnormalities, with second-generation antipsychotics (SGAs) increasing the risk. Low plasma adiponectin levels may lead to metabolic dysregulations but evidence in people with schizophrenia, especially for the role of SGAs, is still inconclusive.
  
  
  OBJECTIVE
  To compare plasma adiponectin levels between people with schizophrenia and healthy controls, and to estimate the relative effect of schizophrenia and SGAs on adiponectin.
  
  
  METHODS
  We performed a systematic review and meta-analysis of observational studies published up to 13 June 2014 in main electronic databases. Pooled standardized mean differences (SMDs) between index and control groups were generated. Appropriate subanalyses and additional subgroup analyses were carried out.
  
  
  RESULTS
  Data from 2735 individuals, 1013 with and 1722 without schizophrenia, respectively, were analysed. Schizophrenia was not associated with lower adiponectin levels (SMD of -0.28, 95%CI: -0.59, 0.04; p=0.09). However, individuals with schizophrenia taking SGAs had plasma levels significantly lower than controls (p=0.002), which was not the case of drug free/drug naïve subjects (p=0.52). As regards single antipsychotic drugs clozapine (p<0.001) and olanzapine (p=0.04)--but not risperidone (p=0.88)--were associated with adiponectin levels lower than controls.
  
  
  CONCLUSIONS
  People with schizophrenia per se may not have levels of adiponectin lower than controls, though treatment with SGAs is associated with this metabolic abnormality. This bears clinical significance because of hypoadiponectinemia involvement in cardiovascular diseases, even if mechanisms whereby SGAs affect adiponectin remain unexplained. Longitudinal studies evaluating long-term effects of SGAs on adiponectin are needed.
authors.affiliation: Department of Surgery and Translational Medicine, University of Milano Bicocca, Via Cadore 48, 20900 Monza, MB, Italy. Electronic address: f.bartoli@campus.unimib.it.
authors.forename: Francesco
authors.initials: F
authors.lastname: Bartoli
authors.affiliation: Department of Surgery and Translational Medicine, University of Milano Bicocca, Via Cadore 48, 20900 Monza, MB, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Lax
authors.affiliation: Department of Surgery and Translational Medicine, University of Milano Bicocca, Via Cadore 48, 20900 Monza, MB, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Crocamo
authors.affiliation: Department of Surgery and Translational Medicine, University of Milano Bicocca, Via Cadore 48, 20900 Monza, MB, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Clerici
authors.affiliation: Division of Psychiatry, Faculty of Brain Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W7EJ, UK.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Carrà
mesh_terms: D052242:Adiponectin / Q000097:blood*; D014150:Antipsychotic Agents / Q000009:adverse effects* / Q000627:therapeutic use*; D006801:Humans; D012559:Schizophrenia / Q000097:blood* / Q000188:drug therapy*
chemical_list: D052242:Adiponectin; D014150:Antipsychotic Agents
keywords: Adiponectin; Cardiovascular diseases; Metabolic abnormalities; Schizophrenia; Second-generation antipsychotics; Weight gain