title: Antipsychotic-induced changes in blood levels of leptin in schizophrenia: a meta-analysis.
abstract: OBJECTIVE
  Weight gain is a major side effect of antipsychotics (APs), which contributes to poor treatment adherence and significant morbidity. The mechanisms involved in AP-induced weight gain are incompletely understood. Recently, it has been proposed that changes in leptin, an cadipocyte-derived hormone exerting anorexigenic effects, may be involved in AP-induced weight gain. Thus far, studies on leptin changes during AP treatment have produced inconsistent results, prompting our group to perform a meta-analysis.
  
  
  METHODS
  A search of the literature was performed using PubMed and Embase. Studies were included only if reporting peripheral levels of leptin before and after AP treatment in schizophrenia. Effect size estimates were calculated with Hedges g and were aggregated using a random effects model as results were heterogeneous (P<0.10). Meta-regression analyses were performed using study length and changes in body mass index (BMI) as moderator variables.
  
  
  RESULTS
  Twenty-eight studies were retrieved, including 39 comparisons. A moderate and positive effect size was observed across studies. Olanzapine, clozapine, and quetiapine produced moderate leptin elevations, whereas haloperidol and risperidone were associated with small (nonsignificant) leptin changes. Across studies, BMI changes were significantly associated with increases in leptin levels. There was no effect of sex on AP-induced changes in leptin.
  
  
  CONCLUSIONS
  A physiological role of leptin in AP-induced weight gain is supported because the most significant leptin increases were observed with APs inducing the most weight gain and because of the observed association between leptin increases and BMI changes. The overall increase in leptin levels suggests that leptin acts as a negative feedback signal in the event of fat increase.
authors.affiliation: Researcher, Centre de recherche de l'Institut Universitaire en Santé Mentale de Montréal, Montreal, Quebec; Associate Research Professor, Department of Psychiatry, University of Montreal, Montreal, Quebec.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Potvin
authors.affiliation: Postdoctoral Fellow, Multiple Sclerosis Research Program, Foothills Medical Centre, Calgary, Alberta; Postdoctoral Fellow, Department of Clinical Neurosciences, Faculty of Medicine, University of Calgary, Calgary, Alberta.
authors.forename: Simon
authors.initials: S
authors.lastname: Zhornitsky
authors.affiliation: Psychiatrist and Professor, Department of Psychiatry, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec; Chair, Department of Psychiatry, Faculty of Medicine, University of Montreal, Montreal, Quebec; Eli Lilly Chair of Schizophrenia, University of Montreal, Montreal, Quebec.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Stip
mesh_terms: D014150:Antipsychotic Agents / Q000009:adverse effects*; D006801:Humans; D020738:Leptin / Q000097:blood*; D012559:Schizophrenia / Q000097:blood* / Q000188:drug therapy*; D015430:Weight Gain / Q000187:drug effects*
chemical_list: D014150:Antipsychotic Agents; D020738:Leptin