DELUSIONS IN SCHIZOPHRENIA SPECTRUM DISORDERS - DIAGNOSTIC ISSUES

Family studies of schizophrenia frequently include relatives of schizo phrenia probands with diagnoses falling within the schizophrenia spect rum. As part of an ongoing genetic linkage study of schizophrenia, the authors examined case material from 50 relatives (of schizophrenia pr obands) who received a DSM-III-R diagnosis of a nonaffective psychotic disorder or schizotypal or paranoid personality disorder. Eleven exhi bited episodic or chronic delusions that resulted in diagnostic dilemm as, often arising from issues pertaining to the classification of delu sional phenomena. Four of these eases are presented here. Unusual beli efs were often difficult to classify as odd beliefs versus full delusi ons, brief/transient versus persistent delusions, bizarre versus nonbi zarre delusions. It is suggested that these might be considered contin uous rather than dichotomous dimensions. Several possible implications for genetic studies of schizophrenia are discussed.