Interpersonal psychotherapy and mirtazapine versus mirtazapine alone in treatment resistant depressed patients with sequential functional brain scans of dopamine D2 receptors with IBZM spect

Abstract

Twenty DSM-IV major depressed patients who had not responded to at least one previous trial of antidepressant therapy at an adequate dose and duration agreed to participate in this study. They were randomly assigned to receive either mirtazapine (30-45mg) alone or in combination with 16 sessions of weekly Interpersonal psychotherapy (IPT). The patients were followed up naturalistically one year, during this time the psychotherapy sessions were delivered monthly Blinded clinician ratings and self ratings were obtained for depression (Hamilton Depression Scale (HamD). Beck Depression Inventory (BD ), anxiety (Hamilton Anxiety Scale (HAS)), and social functioning (Social Adaptation Scale) at baseline, 6, 16, 26 and 52 weeks. I123 Iodobenzamide Single Photon Computed Emission Tomography (IBZM SPECT) scans measured striatal dopamine D2 receptor activity at baseline and after 6 weeks of treatment. A two way repeated measures analysis of variance (ANOVA) detected significant effects measured by the HamD and HAS for time (p= 0.001; p= 0.001 respectively), treatment (p= p= 0.007; p= 0.033) and the interaction between the two (p = 0.007： p = 0.044). Significant differences emerged between the two groups by six months and continued to one year follow up favouring the IPT group (HamD, p= 0.033; HAS, p= 0.003). The only significant effects for the BDI were for time (p= 0.001). There were no statistically significant effects measured by the SAS. A 3-way repeated measures ANOVA on the IBZM SPECT data detected a significant interaction between Time X Hemisphere, demonstrated by a higher IBZM uptake in the striatum in non-responders (p=0.013, agitated patients (p= 0.045) and women (p= 0.012). The same interaction effects were noted in patients with a high level of resistant depression (p= 0.001).This preliminary study shows promising initial results for IPT in resistant depression. There is some evidence to support a role for dopamine in treatment resistant depression.