Are Ratings on the Positive and Negative Syndrome Scale for Schizophrenia Biased by Personality Traits?

Personality dimensions in schizophrenia: A family study

Studies have demonstrated that personality traits differ in schizophrenia patients and family members compared to controls, suggesting familial risk. This study evaluated personality traits in a family study of schizophrenia, as well as the relationship between personality traits and symptoms and social functioning in schizophrenia patients. Thirty-two schizophrenia patients, 28 adult non-psychotic relatives, and 27 community controls completed the Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ). Schizophrenia patients differed on many dimensions of the DAPP-BQ compared to controls and/or relatives: affective lability, anxiousness, callousness, conduct problems, cognitive dysregulation, identity problem, intimacy, insecure attachment, low affiliation, narcissism, oppositionality, restricted expression, self-harm, submissiveness, and suspiciousness. No differences were found between relatives and controls. Furthermore, in schizophrenia patients, associations were found between personality and particularly general symptoms, as well as social functioning. Personality traits can be conceptualized as an extended phenotype in schizophrenia patients.

Associations between the Five-Factor Model personality traits and psychotic experiences in patients with psychotic disorders, their siblings and controls

Earlier studies indicated that personality characteristics contribute to symptomatic outcome in patients with psychotic disorders. The aim of the present study was to further explore this connection by examining the relationship between the Five-Factor Model (FFM) personality traits and a dimensional liability for psychosis. FFM traits according to the NEO-FFI and levels of subclinical psychotic symptoms according to the CAPE were assessed in 217 patients with psychotic disorders, 281 of their siblings and 176 healthy controls. Psychotic symptoms according to the PANSS were assessed in the patient group. Patients differed from siblings and controls on four of the five FFM traits, all but Openness. Siblings reported higher levels of Neuroticism than controls, but lower levels than patients. Particularly lower Agreeableness, and to a lesser degree, higher Neuroticism and lower Extraversion were associated with more severe symptoms in patients. Furthermore, higher Neuroticism and higher Openness were associated with higher levels of subclinical psychotic experiences in all three groups. Associations were strongest in patients. Our findings suggest that levels of Neuroticism increase with the level of familial risk for psychosis. Levels of Openness may reflect levels of impairment that distinguish clinical from subclinical symptomatology.