Melatonin Metabolism Abnormality in Patients With Schizophrenia or Schizoaffective Disorder Treated With Olanzapine

Atypical antipsychotic medications, such as olanzapine, cause metabolic side effects, including weight gain, extra fat around the middle of the body, high blood sugar, and high cholesterol. One of the mechanisms by which these medications may cause these effects is by reducing plasma melatonin. This study is a pilot project to evaluate 1) the effect of olanzapine on melatonin secretion levels and 2) the effect of melatonin on olanzapine-induced changes in melatonin secretion in patients with schizophrenia, schizoaffective, or bipolar disorder.

To investigate the relationship between olanzapine, melatonin, and metabolic functioning, this pilot study is evaluating 20 patients with schizophrenia, schizoaffective disorder, or bipolar disorder over 15 weeks under three experimental conditions: 1) baseline (two weeks treatment with already established antipsychotic medication other than olanzapine or clozapine), 2) six weeks treatment with olanzapine only, and 3) six weeks treatment with olanzapine and melatonin. Half of the patients will receive 0.3 mg of oral melatonin and half will receive 3.0 mg of melatonin. Nocturnal melatonin production, as estimated by assay of urinary 6-sulfatoxymelatonin(aMT6s) adjusted for creatinine, will be measured weekly. In addition, weekly measurements of weight and other metabolic indices, including waist and hip measurements, fasting glucose, serum insulin, cholesterol, triglycerides, and leptin will be taken. It is anticipated that there will be an olanzapine-induced decrease in melatonin production. Furthermore, it is expected that the decrease in melatonin production associated with olanzapine treatment will be reversed by administration of melatonin with olanzapine.