Associations of Common Mental Disorders with Personality Traits Over a 17-Year Period

Changes in personality traits are not unusual, and common mental disorders (CMDs) may play a role. In a large population sample of 55,056 individuals, we examined associations of CMDs recorded in a national registry over 17 years (2004-2021) with self- and informant-rated Big Five personality traits (assessed once in 2021-2022). Besides comparing diagnosed and undiagnosed individuals, we considered the number and timing of CMD records. Those diagnosed with CMDs during the 17-year period differed from undiagnosed individuals by about 0.50 SD higher neuroticism and slightly higher openness. For neuroticism, the difference was greater for those with more recent and numerous diagnoses, whereas for openness, the association did not depend on number or timing of diagnoses. These findings suggest increased neuroticism in response to mental health issues, which may take over a decade to gradually return to baseline, and that less open people may be less likely to seek mental health help. We also found evidence of temporary decreases in extraversion and conscientiousness in response to depressive disorders. Findings were similar in self- and informant-ratings, suggesting they were not assessment artifacts. Our results are consistent with small personality trait changes in response to mental disorders that gradually fade over several years.