Psychostimulants, analeptics, nootropics: an attempt to differentiate and assess drugs designed for the treatment of impaired brain functions.

The common characteristic properties of psychostimulants, analeptics, and nootropics are excitatory and disinhibitory effects on the central nervous system. The differences lie in the type of excitatory effect. Psychostimulants produce a general, yet nonphysiologic, activation with subsequent sedation. They generally act in a destabilising manner, disturbing the homoeostatic functions of centrally regulated reactions. Nootropics produce a physiological activation of disturbed or reduced adaptation functions. They have a stabilising effect, increasing the homoeostatic functions of the centrally regulated reactions that have become susceptible to disturbances. Analeptics differ from psychostimulants and nootropics. The effects of neuronal excitation or disinhibition are mainly restricted to the respiratory and circulatory systems. In high dosages they produce convulsions and corresponding motor reactions. No conclusive evidence for a general efficacy in the treatment of organic mental disorders has been furnished for any of the three drug classes. Yet there is sufficient proof that nootropics, unlike psychostimulants and analeptics, can produce therapeutic results in at least some patients, even if it is not yet clear under what conditions they can be meaningfully applied. There is a fundamental difference between the three groups with regard to the potential for abuse. While tolerance and extreme physiological dependence can occur rapidly under treatment with psychostimulants, such risks are not a typical feature of nootropics or analeptics.