Longitudinal data from a clinical sample of adult female patients with eating disorders was collected, including psychiatric diagnoses, symptoms, personality, and treatment. In Study I, patients were cross-sectionally compared to age-matched controls on personality. Study II examined if personality at admission could predict outcome from group-based psychodynamic day-patient treatment (DAY). Study III examined if personality could predict outcome from internet-based cognitive behavioral therapy (iCBT). In Study IV, personality was assessed at three time points, before treatment, at termination and at six-month follow-up.
Patients differed significantly from controls on the majority of personality traits. Personality could further explain variance in both general and eating disorder specific psychopathology. Extraversion and Assertiveness predicted both eating disorder improvement and remission after DAY whereas both Openness to Experience and Conscientiousness predicted a better outcome from iCBT. Over time, patients decreased in Neuroticism and increased in Extraversion, Openness to Experience and Conscientiousness. There was considerable individual variability in personality change and more than a quarter of patients reliably changed per trait. Patients remitting after treatment showed similar change of increased Assertiveness, Competence, Self-discipline, Openness to Actions, and Positive Emotions. Patients’ personality differed significantly from controls and was associated with both psychopathology and treatment outcome. Personality changed significantly towards normalization, particularly in remitted patients. This project concludes that personality is meaningfully linked to eating disorders and is a malleable aspect of the patient. Greater consideration of personality may help improve treatment.