Personality development from early to middle adulthood in the general population and those with mental health difficulties

Purpose: We describe personality trait maturation from early to middle adulthood in the population and in populations with common mental health or substance use problems to inform personality-sensitive public health and health services care.

Methods: Data were drawn from the population-based Victorian Adolescent Health Cohort Study. Traits were measured using the NEO Five Factor Inventory at 24 and 42 years. We estimated trait rank-order stability, mean-level change, and standardised mean difference (SMD) scores in subgroups defined by patterns of substance use and common mental disorder from adolescence (15-17 years) to adulthood (21-35 years). Multiple imputation was used to address missing data for the full sample of 1,943 participants.

Results: Between early and middle adulthood, population-levels of agreeableness and conscientiousness increased; extraversion, neuroticism, and openness decreased. These patterns were also largely present in those within subgroups, the most pronounced drop being neuroticism in those with persistent common mental disorder (SMD -0.31, 95% CI -0.41 to -0.18). For this group, neuroticism was higher than other traits on entry to adulthood, dropped more substantially than other traits over time, but remained higher than other traits in middle adulthood. A similar decline was not observed for those with no or transient mental disorder, who entered adulthood with lower neuroticism.

Conclusion: Subgroup results for neuroticism imply some variation in the timing of maturation by the presence and duration of common mental disorder. Those who present clinically with long-term anxiety and/or depression may require additional support for midlife personality difficulties that may negatively impact adult roles and functioning.