http://repub.eur.nl/res/aut/51029/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/37996/ 2012-12-04T00:00:00Z There is a long held general belief in society that persons with a major mental disorder are dangerous. The media play an important role in the maintenance of this belief by highlighting cases of violent acts by mentally disordered individuals. Though, during the seventies, this belief became more and more criticized. Studies on the relation between severe mental illness and (violent) criminal offending found no relation between the two. In an extensive research on violent crime by ‘mentally abnormal offenders’ in Germany, Häfner and Böker (1973) concluded that “if we define the dangerousness of the mentally abnormal as the probability of their committing a violent crime, then our findings show that this does not exceed the dangerousness of the legally responsible adult population as a whole” (p. 284). From The Baxstrom Studies (Cocozza & Steadman, 1974), we learned that psychiatry failed in the prediction of dangerousness in the mentally ill. Similarly, in the Netherlands, Tuinier (1989) wrote his dissertation on a field study on the relation between psychiatric syndrome and criminality. He also concluded that psychiatric syndromes (except for abuse disorders) have no relation with criminal offending. http://repub.eur.nl/res/pub/33629/ 2011-09-01T00:00:00Z Patients with schizophrenia and a violent past more often have persecutory delusions than other types of delusions. The main aim of the present study was to examine the relation between persecutory ideation and self-reported aggression in a community based and clinical population. A second aim was to evaluate the psychometric properties of the Dutch version of the Persecutory Ideation Questionnaire (PIQ; McKay, Langdon, & Coltheart, 2006). From the general population, 269 persons were included as well as 79 inpatients from different psychiatric facilities. In the community based sample, the PIQ appeared to be a reliable and valid instrument to measure persecutory ideation. Evaluation of the PIQ in a sample with patients with a psychotic disorder showed that the PIQ had good criterion validity. In addition, results showed that persecutory ideation was significantly related to self-reported aggression in the community based, and in the clinical sample. Moreover, in the community based sample, this association was higher than that between positive psychopathological experiences in general and aggression in the community based sample. In sum, persecutory ideation can be measured reliably with the PIQ, and there seems a robust relation between persecutory ideation in particular and aggression in both clinical and community based samples.