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 (Mage 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.
Plain language summary
The present study investigated how certain negative personality traits, known as the “dark triad”—Machiavellianism, psychopathy, and narcissism change as people grow older. While it is well-known that people generally become more socially desirable in their traits as they move from young adulthood to middle age, less is known about how these dark traits change over time. We analyzed data from over 5,000 people aged 22 to 46, collected over four years. It was observed that both Machiavellianism and psychopathy decreased as people aged, but narcissism stayed about the same. The study also found that people with higher levels of these dark traits tended to experience more depressiveness. As their dark traits decreased, their depressiveness often improved too. Overall, the findings suggest that people with these traits tend to become more socially desirable as they age.