Dimensional personality traits and treatment outcome in patients with major depressive disorder.
BACKGROUND
This study investigated the association between dimensional personality traits from the Five-Factor Model (FFM) and treatment outcome in patients with Major Depressive Disorder (MDD).


METHODS
Six hundred forty-nine outpatients with MDD participated in a randomised double-blind longitudinal study for 6 months. Patients received a combination of medication and psychotherapy; they were randomised to medication condition (tianeptine or fluoxetine), and non-randomly assigned to psychotherapy condition (supportive, cognitive-behavioural, or psychodynamic). The Montgomery Asberg Depression Rating Scale was used to assess depression severity. The Système de Description en Cinq Dimensions was used to assess the personality domains of the FFM.


RESULTS
Group comparisons revealed that patients who responded to both medication and psychotherapy had lower Neuroticism (t=4.22, p<.01), and higher Extraversion (t=4.01, p<.01) and Openness to Experience scores (t=3.57, p<.01) compared to non-responders. Regression analyses, which controlled for shared variance among the five personality domains, indicated that Neuroticism (chi(2)=4.06, p=.04) and Conscientiousness (chi(2)=8.98, p<.01) were significantly and uniquely associated with response. The two-way interactions between NeuroticismxExtraversion (chi(2)=4.49, p=.03) and ExtraversionxConscientiousness (chi(2)=5.91, p=.01) were also associated with response. These results were mostly replicated across the treatment-completer and intent-to-treat samples.


CONCLUSIONS
Dimensional personality traits predict response for individuals with MDD.


CONCLUSIONS
This study did not examine facet-level traits, patient pre-morbid personality and functioning, and additional patient characteristics. Results may not be generalizable to severely depressed or treatment refractory patients.
Quilty
Lena C
LC
Clinical Research Department, Centre for Addiction and Mental Health, Canada.
De Fruyt
Filip
F
Rolland
Jean-Pierre
JP
Kennedy
Sidney H
SH
Rouillon
Pr Frédéric
PF
Bagby
R Michael
RM
D000293:Adolescent; D000328:Adult; D000368:Aged; D015928:Cognitive Behavioral Therapy / Q000379:methods*; D003865:Major Depressive Disorder / Q000188:drug therapy* / Q000453:epidemiology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004311:Double-Blind Method; D005260:Female; D005473:Fluoxetine / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010551:Personality; D010555:Personality Inventory; D011379:Prognosis; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use*; D011795:Surveys and Questionnaires
D005473:Fluoxetine; D017367:Selective Serotonin Reuptake Inhibitors