Nosology

The strength of modern diagnostic systems in psychiatry lies in nosology, that is, in the systematic collection of knowledge and in the description and differentiation of the complex phenomena which become manifest as psychiatric disorders. In consequence, the well-established diagnostic systems ICD-10 and DSM-IV have achieved a high degree of perfectionism, thus representing state-of-the-art instruments for the daily work of clinicians worldwide. Yet these diagnostic systems do not offer clinicians reliable guidelines for therapy and prognosis for a particular patient. In consequence, it is currently impossible to make any prediction of how a particular patient will respond to a particular antipsychotic or antidepressant therapy.

Etiology

Little is known about the etiology of functional psychoses. Even though strong evidence from adoption and twin studies underlines the significance of genetic contributions to the development of these illnesses, the usefulness of psychiatric diagnoses for genetic studies is rather limited, as they delineate the familial aggregation of syndrome patterns insufficiently and do not elucidate the modes of genetic transmission from one generation to the next.

Quantitative Approaches

Multidimensional quantitative approaches to disentangling the complex processes that underlie psychiatric disorders, their development, acute phase, and further course, apparently offer advantages over the qualitative taxonomy of diagnostic systems. Empirical data from our studies carried out over the past two decades clearly support this view, as quantitative syndrome patterns have turned out (1) to resolve the fine gradations of within-family psychopathologies that do nor reach diagnostic thresholds, (2) to model genetic predisposition across ethnicities well compared with epidemiologic data, (4) to relate to the time course of recovery under psychotropic drug treatment, and (5) to lead to a generalized model of genetic vulnerability to functional psychoses, where none of the vulnerability factors by itself is necessary or sufficient for the development of the disorder.

References