Plasma leptin and adiposity during antipsychotic treatment of schizophrenia.

Alterations in plasma leptin have been reported in schizophrenia patients treated with antipsychotics, suggesting the hypothesis that impairments in leptin secretion or signaling might play a role in antipsychotic-induced weight gain. Plasma leptin was measured in 72 schizophrenia patients chronically treated with olanzapine (n=27), risperidone (n=24) or typical antipsychotics (n=21) and 124 healthy adult control subjects. ANCOVA was used to test effects of adiposity (body mass index kg/m2; BMI), subject group (treated patients vs untreated controls), and treatment group (specific medication groups and untreated controls) on plasma leptin concentrations. Additional analyses were performed in a subset of patients and controls individually matched for BMI to further assess group differences in plasma leptin independent of adiposity. BMI strongly predicted plasma leptin concentrations in the overall sample. In addition, a significant three-way interaction between BMI, subject group, and gender was observed. In the individually BMI-matched sample, modestly reduced plasma leptin levels (effect size 0.4 SD) were observed in treated patients in comparison to the BMI-matched healthy controls, with both groups including males and females. However, no differences in plasma leptin levels were observed in the matched sample when separately comparing male patients vs untreated male controls and female patients vs untreated female controls. Plasma leptin in chronically treated patients with schizophrenia is strongly predicted by adiposity, similar to untreated healthy individuals despite adequate power to detect a difference. The results argue against a role for defective leptin secretion or sensitivity in the weight gain induced by antipsychotic medications.

Abnormalities in glucose regulation during antipsychotic treatment of schizophrenia.

BACKGROUND: Hyperglycemia and type 2 diabetes mellitus are more common in schizophrenia than in the general population. Glucoregulatory abnormalities have also been associated with the use of antipsychotic medications themselves. While antipsychotics may increase adiposity, which can decrease insulin sensitivity, disease- and medication-related differences in glucose regulation might also occur independent of differences in adiposity. METHODS: Modified oral glucose tolerance tests were performed in schizophrenic patients (n = 48) receiving clozapine, olanzapine, risperidone, or typical antipsychotics, and untreated healthy control subjects (n = 31), excluding subjects with diabetes and matching groups for adiposity and age. Plasma was sampled at 0 (fasting), 15, 45, and 75 minutes after glucose load. RESULTS: Significant time x treatment group interactions were detected for plasma glucose (F(12,222) = 4.89, P<.001) and insulin (F(12,171) = 2.10, P =.02) levels, with significant effects of treatment group on plasma glucose level at all time points. Olanzapine-treated patients had significant (1.0-1.5 SDs) glucose elevations at all time points, in comparison with patients receiving typical antipsychotics as well as untreated healthy control subjects. Clozapine-treated patients had significant (1.0-1.5 SDs) glucose elevations at fasting and 75 minutes after load, again in comparison with patients receiving typical antipsychotics and untreated control subjects. Risperidone-treated patients had elevations in fasting and postload glucose levels, but only in comparison with untreated healthy control subjects. No differences in mean plasma glucose level were detected when comparing risperidone-treated vs typical antipsychotic-treated patients and when comparing typical antipsychotic-treated patients vs untreated control subjects. CONCLUSION: Antipsychotic treatment of nondiabetic patients with schizophrenia can be associated with adverse effects on glucose regulation, which can vary in severity independent of adiposity and potentially increase long-term cardiovascular risk.