Relationships between IGF-1, schizophrenia, and treatment of metabolic syndrome.

Objectives: The use of atypical antipsychotic drugs in patients with psychiatric illness may result in dyslipidemia, hypertension, glucose intolerance, and abdominal obesity, which are together referred to as metabolic syndrome (MS). To investigate any correlations among insulin-like growth factor-1 (IGF-1), schizophrenia, and MS, we examined the metabolic profiles of patients with schizophrenia taking atypical antipsychotics.

Design: Patients with schizophrenia, their siblings, and controls participated in this study (N=50 in each group). The Structured Clinical Interview for DSM-IV Axis 1 Disorders (SCID I) and the Brief Psychiatric Rating Scale (BPRS) were administered to patients, and SCID I was administered to patients' siblings. We drew blood to measure IGF-1 levels and to determine the metabolic profiles of all participants; we also conducted anthropometric measurements.

Results: There were no significant differences in IGF-1 levels between groups. By comparing IGF-1 levels with MS-related parameters, we found that IGF-1 levels were negatively correlated with triglyceride levels in the control group, and positively correlated with HDL levels in the patient group (Pearson's correlation: r=-0.291, P=0.04, and r=0.328, P=0.02, respectively). Compared to their siblings, patients with schizophrenia had a significantly different body mass index, waist circumference, and insulin resistance, and showed a trend toward a difference in glucose levels (ANOVA: P=0.004, P<0.0001, P=0.004, P=0.072, respectively).

Conclusion: A correlation between IGF-1 and MS may significantly influence future therapeutic strategies for MS. In order to determine the role of IGF-1 in schizophrenia, comprehensive longitudinal studies with first-episode drug-naive patients are needed.