Effects of psychotropic drugs on brain plasticity in humans

Although neurotransmitter-based hypotheses still prevail current thinking about the mechanism of action of psychotropic drugs, recent insight into the pathophysiology of psychiatric disorders has unveiled a range of new therapeutic actions of the drugs used to treat those disorders. Especially antidepressants seem to exert at least some of their effects via restoration of synaptic/neuronal plasticity. In addition, there is increasing evidence that several of the second-generation antipsychotics and some anticonvulsants affect neuronal survival/apoptosis as well as synaptic plasticity. Most of this evidence stems from work in animals. In this review, we will focus on the evidence for neuroplastic effects of psychotropic drugs in humans being aware of the fact that most of the data are derived from animals and that volumetric studies in humans can only indicate structural plasticity and not necessarily functional plasticity. However, as the data from human studies are rather poor and inconclusive, and sometimes even conflicting, it seems impossible to draw general conclusions. Until now studies on neuroplasticity in humans can only explain small pieces of the effects of psychotropic drugs on brain plasticity in humans. Nevertheless, future prospects for the development of new drugs targeting brain plasticity will be of importance and will complete this overview.