Update November 19, 2019
New Direction:
The field of psychiatry has moved from a theory-bound body of medical and psychological knowledge to an empirical approach that is more flexible with regard to reasoning about etiology.
This change came about as it became apparent that developments in neurobiology, genetics, and cognitive and developmental psychology would make unanticipated inroads into our understanding of the etiology and pathogenesis of psychiatric syndromes.
A more flexible philosophy has evolved regarding the description and definition of psychiatric syndromes. Some syndromes have indistinct boundaries and shade into each other. In addition, the idea of discovering a single underlying biochemical characteristic of a psychiatric syndrome, which would in turn clarify the diagnostic description and predict treatment, was recognized as being hopelessly simplistic.
Moreover, through the complexity of behavioral genetics, we now understand that those genotypes which are becoming highly significant in understanding psychopathology and developmental psychology may lead to unexpected phenotypes which do not fit our current conception of the psychiatric syndromes.1