Dopamine metabolism in depressions, psychoses, and Parkinson's disease: the problem of the specificity of biological variables in behaviour disorders.

The probenecid technique was used in study of the central dopamine DA metabolism in patients with depressions, psychotic disorders, and Parkinson's disease. The disturbances found were neither nosologically nor syndromally specific, but appeared to be symptom-specific. Decreased DA turnover was associated with hypomotility, and increased DA turnover with hypermotility. Decreased DA turnover was probably related aetiologically to the hypomotility: the symptoms subsided after replenishment of the DA deficiency. The relation between increased DA turnover and hypermotility is still under investigation. In view of the findings obtained, a plea is made for the development of a functional psychopathology, in which psychiatric syndromes are "dissected" into their constituent psychological dysfunctions. This development is expected to stimulate human brain and behaviour research. It can be achieved only by intensive collaboration between psychiatrists and experimental psychologists.