Background: Appetite, food intake and weight are frequently altered in psychiatric disorders such as major depression and schizophrenia. Leptin is an adipocyte hormone, as the product of the ob gene, regulating food intake and energy balance providing the hypothalamus with information on the amount of body fat. Leptin seems to be strongly associated with lipid metabolism. Moreover, leptin is involved in the control of other behaviors and in brain development. There are few studies about the amounts of plasma leptin in mood disorder and schizophrenia with inconsistent findings. The relationship between leptin and major depressive disorder is still unknown. We planned to investigate the relationship of the serum leptin concentration, cholesterol, and BMI between patients with major depressive disorder, schizophrenic patients and healthy control subjects.
Methods: In the present study, the BMI, plasma cholesterol and leptin levels, BDI, and BPRS were compared in 69 patients with major depressive disorder, 78 schizophrenic patients, and 51 healthy controls.
Results: The major findings of our study included (1) leptin and cholesterol levels were low in patients with major depressive disorder, but high in schizophrenic patients; (2) negative correlations between BDI scores and serum cholesterol or leptin levels in the patients with major depressive disorder; (3) an inconsistently positive correlation between mean leptin levels, cholesterol, and BMI among different groups; (4) positive correlations between serum cholesterol or leptin levels and the length of illness in the schizophrenic patients.
Conclusions: In this study, our results indicate that that leptin and cholesterol might play differently important pathophysiological roles in these psychiatric disorders.