Disentangling within- and between-patient effects of defensive functioning on psychotherapy outcome using mixed models.

Abstract There is a great need to identify predictors of treatment response, and the analysis of defense mechanisms is a promising approach. Defensive functioning may influence psychotherapy outcome in two ways: First, when it is generally higher or lower for some patients relative to others and second, as it shifts in individual patients over time. The present study examined both within- and between patient effects of defenses using hierarchical linear modeling. Forty-seven patients diagnosed with depression, anxiety, or adjustment disorders received 25 ± 3 sessions of integrative cognitive-behavioral therapy in a university outpatient clinic. The Defense Mechanism Rating Scale (DMRS) was used to assess defenses in the 1st, 8th, 16th, and 24th session and relate them to symptom severity of depression and anxiety. A higher number of adaptive defense mechanisms was associated with less severe depressive symptoms during treatment while a higher number of immature defenses was related to more severe depressive and anxiety symptoms. An increase in adaptive and a decrease in immature defenses over the course of treatment predicted symptom reduction of depression whereas a decrease in neurotic and immature defenses was associated with reductions in anxiety symptoms. Our results empirically support defensive functioning as a mechanism of change in psychotherapy.