German researchers have found that personality traits and depression symptoms change in interconnected ways during inpatient treatment. In people with a higher average level of neuroticism - a tendency toward frequent negative emotions such as anxiety and despondency - improvement across many depression symptoms was slower. And in those more inclined toward extraversion (sociability, energy) or agreeableness (willingness to cooperate and trust), recovery, on the contrary, proceeded faster. The results were published in the Journal of Affective Disorders.
The study involved 334 patients in the psychiatric department of a university clinic in Germany. They had been diagnosed with affective or psychotic disorders, including major depressive disorder and bipolar disorder. To be included in the analysis, a patient had to spend at least four weeks in the hospital - a period sufficient to track the dynamics.
Patients filled out digital questionnaires on admission, then roughly every two weeks and shortly before discharge. One questionnaire assessed the severity of 21 depression symptoms over the previous two weeks - from depressed mood and suicidal thoughts to sleep and appetite disturbances. Another measured the five main personality traits, the so-called "Big Five": neuroticism, extraversion, openness to experience, agreeableness and conscientiousness (organization and reliability). To avoid overburdening patients, a very short 15-item version of the test was used.
During treatment, overall depression severity decreased noticeably. At the same time, self-descriptions of personality also changed: neuroticism became lower, while conscientiousness and extraversion became higher. Statistical models showed that these shifts were linked: the more strongly neuroticism fell, the more strongly overall depression severity also decreased. For agreeableness, conscientiousness and extraversion, the picture was the reverse - the more the trait grew, the more noticeably mood improved. Importantly, this is a correlation, that is, a statistical association that by itself does not prove that personality traits directly cause changes in symptoms.
The scientists then broke depression down by individual symptoms. Higher average neuroticism was associated with slow improvement in 14 symptoms - among them sadness, irritability, suicidal thoughts, insomnia, loss of appetite and somatic complaints. High extraversion corresponded to faster relief of seven symptoms, including difficulties with work, indecisiveness and pessimism. Agreeableness - to a faster decline in self-blame, guilt and dissatisfaction with one's body. Openness - to a quicker return of sexual interest and a reduction in feelings of guilt. Conscientiousness turned out to be the only trait that did not show such links with the rate at which individual symptoms disappeared, although overall it rose as the condition improved.
The authors emphasize limitations. The observation took place in natural conditions, patients received different treatments and for different lengths of time, so it cannot be asserted that personality traits directly caused changes in symptoms. The short personality questionnaire is less precise, especially for extraversion. In addition, it is difficult to separate genuine character changes from a return to a usual state as depression lifts: in a depressed state, people tend to see themselves in a negative light. Future work could observe patients for months and years after discharge and use more complete tests.
If the link is confirmed, psychiatrists will be able to offer targeted help earlier. For example, with high neuroticism - emotional regulation training and work with intrusive thoughts, and with high extraversion - group therapy with active communication. For now, however, these are only hypotheses requiring verification.