β-Cell Function in Schizophrenic Subjects on Atypical Antipsychotic drugS

Phase 1 Study of Insulin Sensitivity, Adjusted β-Cell Function and Adiponectin Among Lean Drug-naïve Schizophrenic Subjects Treated With Atypical Antipsychotic Drugs

The purpose of this study is to determine whether atypical antipsychotic drugs (commonly prescribed for treating schizophrenia) induce changes in anthropometry and metabolism, including alteration in insulin sensitivity and/or insulin secretion by the pancreas, when given to lean, non-diabetic, individuals who are antipsychotic drug(s)-naïve, and free of metabolic syndrome at enrollment.

Atypical antipsychotic drugs (AADs) induce weight gain, truncal adiposity and may engender a metabolic syndrome which may progress to IFG/IGT or DM. AADs effects in lean schizophrenic patients without metabolic syndrome are not documented, especially the relationship between weight gain and changes in insulin sensitivity (S), beta-cell function (β), and circulating adiponectin. We prospectively determined the outcome of 9-month therapy with AADs on anthropometrics, metabolism and adiponectin, including HOMA-modeling of S, β, and βxS (hyperbolic product, assessing individual β adjusted for S)in 36 schizophrenic subjects (M:F 24:12; Caucasian n=23; North-African n=12; South-Asian n=1) aged 35±9 years (mean±1SD) free of MetS (NCEP-ATPIII).

Inclusion Criteria:

• age 18-55 years
• body mass index <25.0 kg/m²
• waist circumference <102 (men) and <88 cm (women)
• absence of a metabolic syndrome according to NCEP ATPIII criteria
• normoglycaemic (fasting plasma glucose levels <100 mg/dl)

Exclusion Criteria:

• previous use of antipsychotic drugs
• concomitant therapy with drugs known to possess an inherent potential to increase weight and/or to alter glucose metabolism (including antihistaminic drugs, glucocorticoids, β-blockers, antiepileptic drugs and mirtazapine)