A sib-pair study of psychoticism, life events and depression

The Psychoticism (P) scale of the Eysenck Personality Questionnaire (EPQ) (Eysenck & Eysenck, 1975) was originally proposed as a measure of the predisposition to psychotic breakdown, however, subsequent research has suggested that the P-scale is measuring a thoughtless and reckless personality. This study aims to further examine the construct of P, its relation to the experience of adversity and the development of depression. One hundred and eight depressed probands and their nearest aged siblings were compared to 105 control probands and their nearest aged siblings. All were interviewed using the Schedule for the Clinical Assessment of Neuropsychiatry (Wing, Babor, Brugha et al., 1990) and the Life Events and Difficulties Schedule (Brown & Harris, 1978). Subjects also completed the Beck Depression Inventory (BDI) (Beck, 1961) and the EPQ at the time of interview. It was found that four factors underlie the P-scale, namely Cruel/ Hostile, Anti-social, Impulsiveness, Recklessness/Fecklessness. The P-scale is familial and scores correlate positively with severe and threatening life events and BDI score at the time of interview. It is concluded that high P-scale scorers are predisposed to personality traits that are associated with an excess of severe and threatening life events, which in turn can lead to the development of depression.