What future directions for depression research emerge from this study? One important aspect
may be the trait–state continuum. Although interpersonal styles are considered relatively stable
traits, depression severity is assumed to vary with psychological health. More longitudinal
studies are needed that assess the temporal stability of symptoms, interpersonal problems, and
personality characteristics (Grosse Holtforth, Lutz, & Grawe, 2006). These studies also bear
the potential of disentangling mediation effects between interpersonal dispositions, current
interpersonal problems, and depression. Because relatedness and self-definition are assumed to
be fundamental personality dimensions, a link with the personality literature around the Big Five,
especially neuroticism and agreeableness, also appears important. A better understanding of the
causal relations between interpersonal personality variables at different levels and depression
may lead to an adaptation of treatment approaches