Neurodegeneration, Neuroregeneration, and Neuroprotection in Psychiatric Disorders.

Prevention of deterioration of brain function over time is important in the long-term management of chronic brain disorders such as dementia, schizophrenia, and mood disorders. Although the possibility of neurogenesis in the adult human brain is attractive, and there are psychiatric drugs proven to be effective inducers of neurogenesis in animals, we have yet to see their utility in clinical practice. The terms neurodegeneration and neuroregeneration are often used in a nonspecific manner. Neuroregeneration may mean neurogenesis, dendritogenesis, spinogenesis, or axonogenesis. The term "neuroprotection" is attractive clinically and may involve different mechanisms. Many causative and protective factors of neurodegeneration and neuroregeneration have been proposed. However, the specificity of these factors and agents and differential neuronal vulnerability factors have generally been ignored in past studies. It is also hard to separate disease-modifying from "neuroprotective" effects of a drug. The application of stringent long-term neuroanatomical, neurochemical, neurophysiological, and therapeutic efficacy criteria should improve future research in this important area.