An open study of triiodothyronine augmentation of selective serotonin Reuptake inhibitors in treatment-resistant major depressive disorder

Objective: In an open trial, we investigated the efficacy of triiodothyronine (T,) adjuvant to selective serotonin reuptake inhibitors (SSRIs) in subjects with major depressive disorder (MDD) resistant to SSRI treatment. Method. Twenty subjects who met DSM-IV criteria for MDD (mean +/- SD age = 44.3 +/- 10.3 years; 55% [N = I I] women) and had failed to respond to a course of treatment of at least 8 weeks with an SSRI antidepressant were enrolled in a 4-week open-label augmentation treatment with T-3 50 mu g/day. Atypical and melancholic subtypes of MDD were diagnosed using Structured Clinical Interview for DSM-IV Axis I Disorders criteria. We administered the 17-item Hamilton Rating Scale for Depression (HAM-D-17) 4 times during the study (which was conducted between 2001 and 2003). Results: During T3 augmentation, the severity of depression decreased from an initial mean SD HAM-D-17 score of 20.5 +/- 3.6 to a final HAM-D-17 score of 14.0 +/- 7.1 (p < .001). Seven subjects (35.0%) were treatment responders (HAM-D-17 reduction >= 50%), and 6 subjects (30.0%) achieved clinical remission (final HAM-D-17 : 7). The 5 subjects with atypical depression experienced significantly (p < .01) greater clinical improvement (final HAM-D-17 scores 6.6 +/- 1.8 vs. 16.4 +/- 4.5), and higher rates of treatment response (100% [5/5] vs. 13.3% [2/15]) and remission (80.0% [4/5] vs. 13.3% [2/15]), compared to subjects with nonatypical MDD. The 8 subjects with melancholic MDD experienced significantly (p < .05) greater depression severity at the end of the study compared to nonmelancholic MDD subjects (final HAM-D-17 scores = 18.3 +/- 6.6 vs. 11.1 +/- 6.1). Conclusion: Triiodothyronine augmentation of SSRIs may be a promising treatment strategy in SSRI-resistant MDD, particularly in subjects with the atypical MDD subtype.