Delusional Psychoses: Genetic Findings as a Critical Variable for the Validation of Diagnostic Criteria

Abstract

77 patients with delusional psychoses, regardless of their nosological attribution (except severe organicity), and their first-degree relatives were diagnosed with the Research Diagnostic Criteria (RDC) and the Vienna Research Criteria (VRC). The diagnostic procedure was performed blindly in the relatives. Both criteria were sufficiently capable of identifying a schizophrenic and affective subgroup of patients characterized by the appearance of homotypical secondary cases. Apart from a small RDC schizoaffective group differing in genetic pattern, there exists another large group of nonschizophrenic, nonaffective delusional disorders lacking a genetic link to the above-mentioned diagnoses. In respect to the development of the diagnostic criteria, the results of this study call for the formulation of (1) a narrow definition of schizophrenia (as in the VRC) which is based on thought disorder and affective blunting with the exception of so-called productive symptomatology (delusions, hallucinations); (2) separate criteria for schizoaffective disorders (as in RDC), and (3) a broad and nonrestrictive definition for nonschizophrenic delusional disorders.

Delusional Disorder and Mood Disorder: Can They Coexist ?

“…If this hypothesis was corrected, the risk for affective illness in relatives of delusional disorders ought to sub stantially exceed that found in the general population. Our data, in agreement with pre vious studies [2,8,14,15], do not support the view that delusional disorder is closely related etiologically to mood disorder.…”

“…For diagnostic, therapeutic and prognostic pur poses, it is then useful to set the boundaries and understand the relationships of the two conditions. The Vienna Research Group has spent a great effort over the past 25 years in the analysis of paranoid psychoses: they iden tified a homogeneous subgroup within para noid psychoses that they called cyclothymic axial syndrome, in which mood features were present [1][2][3][4], Recently. DSM III-R [5] prompted efforts to define the principles of differential diagno sis to be used for patients with both psychotic and full affective syndromes.…”