[Leptin and psychiatric disorders]

As early as the beginning of the 20th century, changes in appetite and weight were recognized as important symptoms of severe psychiatric disorders. Particularly in the last decade, understanding of the regulation of appetite and weight has made major progress. In this context, the discovery of the adipose tissue hormone leptin, which signals the size of the peripheral fat stores to the CNS, was crucial. In addition, leptin is also involved in a number of CNS networks regulating behavior and thus of great importance for the pathophysiology of psychiatric disorders. Apart from sexual behavior, those networks include motor activity, sleep, and cognition. Moreover, leptin seems to be involved in the development and maturation of the brain. The present paper summarizes current studies which suggest that, in psychiatric disorders, leptin could be of importance not only for disease-associated or drug-related changes in appetite and weight but also for alterations in behavior and cognition.