Self-report screening instruments are able to distinguish
between psychosis-proneness individuals and those devoid of a psychotic-like
cognitive style.
Mental disorders with psychotic features are relatively rare but severely impairing syndromes that negatively impact on the life of those affected by them, increasing their risk of premature mortality and reducing their social, relational and occupational adjustment.
Upon taking into account all the different diagnostic categories expressed with psychotic features, including schizophrenia, schizoaffective disorder, chronic delusional disorder, bipolar disorder, and major depression with psychotic features, it was found that prevalence rates for psychotic disorders in the general population range around 3%, for narrow criteria, and 10% for broader criteria.
Nevertheless, for mental disorders with psychotic features there is still a lack of well-grounded measures, and the validity of the proposed instruments is far from being ideal.
Recent studies carried out in Sardinia
by Doctor Antonio Preti, in collaboration with the Department of Psychology of
the University of Cagliari, found that a well-validated measure of the risk of
psychosis, the Peters
et al. Delusions Inventory (PDI), can be used to investigate the correlates of
psychosis in non-clinical samples.
The PDI,
aimed at investigating psychosis-proneness in the general population, proved
reliable enough and valid in distinguishing people diagnosed with a psychotic
disorder from putatively healthy people (Preti, Rocchi,
et al., 2007).
Furthermore, in a large sample of 604 Italian healthy subjects (248 males, 41.1%; 356 females, 58.9%; mean age=34.5±11.9), mixed-handed were found to score statistically higher on the PDI than the right-handed and left-handed (Preti, Sardu, et al., 2007), a finding compatible with the leftward shift in the handedness distribution frequently observed among patients with schizophrenia compared to controls.
The study of indexes of psychosis-proneness in non-clinical samples looking for biological and cognitive markers of schizophrenia might be a useful addendum to clinical studies, concluded Dr Preti, since it allows the investigation of testable models without the crux of severe psychotic symptoms and the interference due to multiple biological effects of drug therapy.
Reference:
Antonio Preti, Marco BL Rochi, Davide Sisti, Tania Mura,
Sebastiana Manca, sara Siddi, Donatella Rita Petretto, Carmelo Masala
Comprehensive Psychiatry, 2007; 48:
62-69.
Antonio Preti, Cinzia Sardu,
Annalisa Piga
Schizophrenia Research, 2007; 92:
15-23.
Contacts:
Dr Antonio Preti
SchizophreniaProject
e-mail: apreti@tin.it