An 18-year cohort study suggests people with persistent anxiety or depression may still mature emotionally over time, but may need more support as elevated neuroticism persists into middle age.
Study: Personality development from early to middle adulthood in the general population and those with mental health difficulties. Image Credit: KieferPix / Shutterstock
A recent study published in the journal Scientific Reports suggests that the timing of maturation may vary by mental health status. People with persistent common mental disorders (CMDs) may experience personality maturation later in adulthood than the general population. These individuals may also continue to experience greater emotional instability in middle age, although to a lesser extent than during early adulthood. Understanding these patterns could inform targeted public health interventions.
Clinicians may consider additional support for emotionally vulnerable individuals. Recognizing that personality maturation may occur on a different timeline in some individuals could also help reduce stigma around emotional difficulties and encourage earlier support.
Personality traits shape various life outcomes, including health, relationships, career, social communication, and how individuals respond to everyday situations. Understanding how these traits change could improve insights into human behavior and support more personalized mental care.
All individuals also do not mature and process emotions in similar ways. Some individuals mature faster than others, and some may perceive situations more negatively. If clinicians can identify individuals who may exhibit signs of delayed personality maturation or heightened emotional vulnerability, they can tailor their treatment strategies to improve emotional well-being.
About the study
In the present study, conducted from 1992 to 2021, researchers examined changes in personality traits over time in the general population and among individuals with CMDs during early and middle adulthood (ages 24 to 42).
The team analyzed data from the 1992 Victorian Adolescent Health Cohort Study (VAHCS). The sample population comprised 1,943 individuals. The researchers classified CMD and substance use patterns into four groups: not present, adolescent-only, adulthood-only, and present during both adolescence and adulthood. Individuals aged 15 to 17 years were classified as adolescents.
Participants aged 21 to 35 years were considered adults. Only individuals studying Year 9 in secondary schools in Victoria were included in the adolescent group. Adolescent data were collected using in-school computer-administered questionnaires, while adult data were collected through computer-assisted telephone interviews and online questionnaires.
The researchers used the NEO Five Factor Inventory (NEO-FFI) to assess personality changes. For each trait, they evaluated its stability over time and calculated the standardized mean difference (SMD). The team assessed CMD symptoms using the General Health Questionnaire (GHQ-12), Revised Clinical Interview Schedule (CIS-R), and Composite International Diagnostic Interview (CIDI). They identified substance use problems using the Fagerstrom Test for Nicotine Dependence (FTND) and CIDI.
The researchers collected data every 6 months from participants aged 14-17 years. They conducted five follow-up rounds of data collection for individuals aged 42 years or younger. They used the multiple imputation method to account for missing data. The analysis was descriptive and used unadjusted estimates, meaning the findings should not be interpreted as evidence that CMDs caused personality changes.
Results
During the study period, among participants with available CMD classification data, approximately one-third experienced CMDs in both adolescence and adulthood, one-third experienced a disorder in either stage alone, and the remaining one-third experienced none in either stage. Substance use problems were relatively more common. Among participants with available substance-use classification data, 42.7% had substance use problems during both adolescence and adulthood.
The personality traits showed generally predictable patterns from early to middle adulthood. At the population level, conscientiousness and agreeableness increased, whereas extraversion, openness, and neuroticism decreased with time. Participants showed the most significant decline in extraversion (SMD, −0.38), while neuroticism decreased more modestly overall (SMD, −0.11). Most traits remained moderately stable over time (rank-order stability coefficient, 0.4 to 0.5). Openness was the most stable personality trait across the study period.
Personality development varied by mental health status. Over the years, participants with persistent CMDs became increasingly agreeable (SMD, 0.4) and emotionally stable, with a significant decrease in neuroticism (SMD, -0.3). Nevertheless, these individuals showed higher baseline neuroticism scores, which remained higher than those of the general population even in middle age.
These observations indicate that although people with CMDs become increasingly emotionally stable with time, their neuroticism levels continue to be higher during middle age than among those without such disorders. Participants without persistent CMDs generally followed the population-level patterns of personality development.
Substance use problems were associated with subtle changes in personality development. A decrease in openness was clearest among those with adolescent-limited substance use problems, while neuroticism decreases were most distinctive among those with persistent or adulthood-only substance use problems. However, confidence intervals overlapped across substance-use subgroups, and overall personality changes were modest. Agreeableness, conscientiousness, and extraversion followed similar developmental patterns regardless of substance use history.
Implications
The study findings suggest that people with persistent common mental disorders may show a different timetable for emotional-stability maturation, with changes observed between early adulthood and midlife.
Those presenting clinically with persistent anxiety or depression may benefit from additional personality-sensitive support, particularly if elevated neuroticism or delayed emotional-stability maturation affects adult roles and functioning. Their neuroticism may reduce over time, but may remain higher than levels observed in the general public in middle age.
Clinicians may therefore need to modify their treatment approaches to account for each individual’s emotional and psychological profile, supporting personalized and holistic care. If confirmed in larger studies analyzing more personality traits, assessments of personality development could one day help identify individuals who may benefit from additional psychological support.
The authors noted several limitations. Personality was assessed at only two time points, meaning the study could not pinpoint when changes occurred between the twenties and early forties. Personality traits were self-reported, missing data were higher for CMD and substance-use classifications, and the overlap between neuroticism and symptoms of anxiety or depression should be considered.
The researchers also noted that regression to the mean may partly explain declines in neuroticism among those with higher baseline scores. Future studies using more frequent personality assessments and independent datasets could help clarify whether these patterns replicate across other populations.
Download your PDF copy by clicking here.
Journal reference:
Kerr, J.A., Dashti, S.G., Husin, H.M. et al. (2026). Personality development from early to middle adulthood in the general population and those with mental health difficulties. Scientific Reports, DOI: 10.1038/s41598-026-55483-z, https://www.nature.com/articles/s41598-026-55483-z