Background: We aimed to determine the relationship between certain personality disorders and/or personality traits and early onset major depression.
Methods: A total of 400 depressed primary care patients were assessed for personality disorders using the SCID screen and for personality traits using the Karolinska Scales of Personality (KSP) questionnaire. Early onset was defined as onset of the first episode before the age of 26. Logistic regressions were performed to reveal relationships after adjustment for sex, age and number of previous episodes.
Results: Both groups had a similar severity of current illness determined by the Montgomery-Asberg Depression Rating Scale. Those with an early onset presented with a more debilitating course, seen in the form of more depressive episodes and previous hospitalisations in spite of their younger age. Early onset was also an independent predictor for avoidant, borderline and paranoid personality disorders. It also predicted increased scores on the KSP scales Psychic anxiety, Psychasthenia, Muscular tension, Suspicion and Irritability, and decreased Socialisation.
Limitations: The evaluation was performed as a self-assessment, subjects had a superimposed major depressive episode when assessed, and subgroups of individuals were not eligible.
Conclusions: Early onset major depression is a predictor for personality pathology and deviant personality traits. A better understanding of the interplay between genetics and environment that underlies this phenomenon will help to improve the long-term course in afflicted individuals.