Background: There is a paucity of treatment options for bipolar depression. The use of triiodothyronine (T3) has been suggested as adjunctive treatment.
Methods: A search on Medline, Limo and ScienceDirect was performed using the search terms bipolar disorder, bipolar depression, treatment resistant, treatment refractory, thyroid hormones, triiodothyronine, T3, acceleration and augmentation.
Results: We retrieved three open studies, one comparative study, two double blind and one retrospective chart review. The three open studies observed improvement in respectively 56%, 75% and 79% of patients, the retrospective chart review noted improvement in 89% of cases and the mirror design showed improvement in 66%. In the comparative study T3 performed significantly better than placebo. The only randomized double blind study could not prove any substantial difference between T3 and placebo.
Limitations: Available studies are scarce and flawed. All have (very) low number of subjects: overall, only 353 subjects and only 194 of which in prospective trials. In only two of the prospective trials bipolar patients were analyzed separately. Comparing the studies is hampered by a high variability in assessment tools, baseline medication and degree of treatment-resistance.
Conclusions: The few available studies are small and flawed. They do show promising results. We found many clues suggesting that T3 could augment and accelerate treatment response not only with antidepressants, but also with lithium and perhaps with other treatment options, that it might protect against rapid cycling bipolar disorder, as well as against relapse during the first few years of treatment.
Keywords: Bipolar depression; Bipolar disorder; Triiodothyronine.
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