Abstract
OBJECTIVE: Dimensional personality trait models have gained favor as an alternative to categorical personality disorder (PD) diagnosis; however, debate persists regarding whether these traits should be conceptualized as maladaptive at both extremes (i.e., maladaptively bipolar) or just one trait pole (i.e., unipolar). METHOD: To inform the debate on maladaptive bipolarity, linear and nonlinear relations between personality traits and dysfunction were examined in a large psychiatric patient sample (N = 365). Participants self-reported on normal-range and pathological personality domains, life satisfaction, specific interpersonal problems, and broad psychosocial functioning. In addition, participants were interviewed regarding specific psychiatric symptoms and broad psychosocial functioning. RESULTS: All traits related moderately to strongly with at least one dysfunction variable. All traits were predominantly correlated with dysfunction at one pole; however, several small linear relations provided some evidence for maladaptively high Extraversion and Agreeableness. None of the significant nonlinear effects provided clear evidence for maladaptivity at both ends of any trait. CONCLUSIONS: Taken together, these results suggest that broad personality traits are predominantly maladaptive at one extreme; however, in limited cases, the opposite extreme may also be maladaptive.