Abstract
Weight changes during pharmacological treatment are a well-known phenomenon and they have been an object of research since the 1950's. Weight gain occurs during treatment with drugs of different chemical structures and is an important problem when patients are treated with antidepressants, antipsychotics, or mood stabilizers. The clinical relevance of drug-induced weight changes is due to increased rates of morbidity and reduced treatment compliance. Regarding the underlying causes, the important role of neurotransmitter systems and in particular the blockade of serotonin and histamine receptors has been discussed since decades. Only recently, however, research has been started on the effects of psychotropic agents on major neuroendocrine systems involved in appetite and weight regulation. These studies suggest that the fat-cell derived hormone leptin might play an important role. Leptin signals to the brain the size of the adipose tissue and is probably the most important peripheral signal for the long-term regulation of weight. In addition to the neuroendocrine systems, weight gain induced by psychotropic agents might also involve immune modulators, in particular the proinflammatory cytokine tumor-necrosis-factor-alpha (TNF-alpha) and soluble TNF-receptors. Some psychotropic agents influence the TNF system very rapidly, already prior to any obvious increases in weight. Hence, changes in the TNF-alpha system might be of predictive value for drug-induced weight gain. Strategies to minimize or to counteract weight gain induced by psychotropic agents include psychotherapeutic and pharmacological approaches. Although numerous psychotherapeutic approaches are available, they are only of limited usefulness in severely ill psychiatric patients. Fortunately, a number of promising pharmacological approaches to reduce weight have been introduced into clinical practice during the last years; however, so far there is no knowledge on pharmacodynamic and -kinetic interactions with psychotropic drugs, and there is no clinical data on the usefulness and safety of such drug combinations.