Abstract
Three generalizations of drug action appear to be crystallizing: (1) Mental depression may be related to either a neurohumoral deficiency of cerebral serotonin or some sympathomimetic amine or to some enzyme disorder such as a monoamine oxidase overactivity in the adrenergic excitatory mechanisms of the brain which might produce such a deficiency. (2) Drugs which are most effective in curbing the acute mania, motor excitement and hallucinations of the schizophrenic reaction are those which interfere in some manner with the adrenergic excitatory centers for emotional responses in the brain as exemplified by reserpine and chlorpromazine. (3) Psychoneurotic symptoms respond most favorably to drugs which have a minimum of side effects and produce a relaxation of neuromuscular tension and anxiety with a minimum of drowsiness and other symptoms of central nervous system depression.