Changes in Psychological Need Fulfillment Over the Course of Treatment for Major Depressive Disorder

Self-determination theory (Ryan & Deci, 2017) maintains that the psychological needs for autonomy, competence, and relatedness are essential qualities of experience that individuals require to thrive. The present research examined the role of psychological need fulfillment in a clinical sample undergoing treatment for major depressive disorder. Fifty-one patients with a SCID-IV diagnosis for major depressive disorder were randomly assigned to 16 weeks of cognitive behavioral therapy or antidepressant medication. Depressive symptoms, cognitive errors, dysfunctional attitudes, and psychological need fulfillment were assessed at four time points (pre-treatment, week 4, week 8, and week 16). Psychological need fulfillment increased over the course of treatment and did not differ significantly between treatment conditions. Furthermore, increases in psychological need fulfillment were associated with decreases in depression severity over and above the effects of time, cognitive errors, and dysfunctional attitudes. Given the incremental predictive validity of need fulfillment, a better understanding of its role in the treatment for depression may prove beneficial to mental health researchers and practitioners.