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), such as anxiety, depression, and alcohol use disorder, may play a role. In a large population sample of 55,056 individuals, we examined the associations of CMDs recorded in a national registry over 17 years with self- and informant-rated Big Five personality traits. Besides comparing diagnosed and undiagnosed individuals, we considered the number and timing of the CMD records. Those diagnosed with a CMD during the 17-year period differed from undiagnosed individuals by about 0.50 SDs higher neuroticism and slightly higher openness. For neuroticism, the difference from undiagnosed individuals was greater for those with more recent and more numerous diagnoses, whereas for openness, the association did not depend on the number or timing of diagnoses. These findings are consistent with increased neuroticism in response to mental health issues, which may take more than a decade to gradually return to the baseline, and with less open people being less likely to seek help for mental health issues. We also found evidence consistent with temporary decreases in extraversion and conscientiousness in response to depressive disorder. The findings were consistent across self- and informant-ratings, suggesting they were not assessment artefacts. This study, the largest to date, suggests that some personality trait changes in response to mental disorders may persist for at least a decade, much longer than previously thought.