Codevelopment of the dark triad and depressiveness from emerging adulthood to midlife

Personality development from emerging adulthood onwards is marked by traits becoming more socially desirable. However, little research exists on developmental trends of so-called dark personality traits. Moreover, the current understanding of longitudinal trends and associations with mental health remains unclear. Addressing this gap, the present study analyzed average (mean-level) changes of the dark triad traits (Machiavellianism, psychopathy, and narcissism) in three birth cohorts over a 4-year period spanning emerging adulthood to midlife, as well as their concurrent and longitudinal associations with depressiveness. We used three data waves, each 2 years apart, from the German Family Panel ( pairfam) to perform growth curve models. The final sample included N = 5,127 participants ranging from 22 to 46 years ( M age at T1 = 34.59). Results indicated a significant linear downward trend for Machiavellianism and for psychopathy but no linear change in narcissism. All dark triad traits had moderate positive correlations with depressiveness, and changes in these traits showed moderate to strong correlations with changes in depressiveness. Overall, the findings suggest that from emerging adulthood into midlife, individuals high in Machiavellianism and psychopathy develop towards greater social desirability.