Predicting individual change in personality disorder features by simultaneous individual change in personality dimensions linked to neurobehavioral systems: the longitudinal study of personality disorders.

Personality disorders (PDs), long thought to be immutable over time, show considerable evidence of individual change and malleability in modern prospective longitudinal studies. The factors responsible for the evident individual change in PDs over time, however, remain essentially unknown. A neurobehavioral model that posits negative emotion (NEM), nonaffective constraint (CON), communal positive emotion (PEM-C), and agentic positive emotion (PEM-A) as important systems underlying PD provides a theoretical basis for investigating predictors of change in PD features over time. Thus, in this study, the authors investigated how individual change in NEM, CON, PEM-C, and PEM-A over time predicted individual change in PD features over time, using longitudinal data on PD assessed by the International Personality Disorders Examination (A. W. Loranger, 1999), as well as data on normal personality features gathered within a 4-year prospective multiwave longitudinal study (N = 250). The authors used the method of latent growth modeling to conduct their analyses. Lower initial levels of PEM-C predicted initial levels of the growth trajectories for those with elevated Cluster A PD features. Elevated NEM, lower CON, and elevated PEM-A initial levels were found to characterize the initial levels of growth trajectories for those with increased Cluster B PD features. Interestingly, subjects with higher initial levels of PEM-A revealed a more rapid rate of change (declining) in Cluster B PD features over time. Elevated NEM and decreased PEM-C initial levels were found to characterize the growth trajectories for subjects with increased Cluster C PD features. The substantive meaning of these results is discussed, and the methodological advantages offered by this statistical approach are also highlighted.