Thyroid Hormone and Depression

Symptoms of hypothyroidism and of hyperthyroidism tended to decrease on a standard symptom scale after combined (T4 and T3) treatment. With combined hormone replacement, mental state tended to improve on some mood scales but not on cognitive tests?.These preliminary findings in a small group of patients with Graves’ disease are consistent with earlier findings that thyroid replacement with T4-T3 combination improves mental functioning.

Bunevicius R et al. Thyroxine vs thyroxine plus triiodothyronine in treatment of hypothyroidism after thyroidectomy for Graves’ disease. Endocrine 2002 Jul;18(2):129-3

After combined (T3 and T4) hormone treatment there were clear improvements in both cognition and mood, the latter changes being greater.

Bunevicius R et al. Mental improvement after replacement therapy with thyroxine plus triiodothyronine (T3): relationship to cause of hypothyroidism. Int J Neuropsychopharmacol 2000 Jun;3(2):167-174.

Addition of T3 was effective [for treating depression] in 10 out of 16 women (62.5%) while none of the 9 males responded. Although values were within the normal range, patients who responded to T3 had higher serum thyroid-stimulating hormone levels than those who did not?.The effect of T3 may be related to thyroid function even within the normal range.

Agid O et al. Algorithm-based treatment of major depression in an outpatient clinic: clinical correlates of response to a specific serotonin reuptake inhibitor and to triiodothyronine augmentation.Int J Neuropsychopharmacol 2003 Mar;6(1):41-49.

Depressed patients should be screened for hypothyroidism. In hypothyroid patients, depression may be more responsive to a replacement regimen that includes T3 rather than T4 alone. Therefore, inclusion of T3 in the treatment regimen may be warranted after adequate trial with T4 alone.

Rack SK et al. Hypothyroidism and Depression: A Therapeutic Challenge. Ann Pharmacother 2000 Oct;34(10):1142-5.

We now report on the successful use of T3 augmentation therapy in seven of nine depressed patients who were also receiving T4 for thyroid disease?.Seven of the nine patients were judged to respond to T3 augmentation. CONCLUSION: These results are consistent with a report of differential effects for T3 versus T4 augmentation in depressed patients free of thyroid disease. The results have implications for the treatment of depression in the presence of thyroid disease and for the mechanism of thyroid hormone potentiation of antidepressants.

Cooke RG et al. T3 augmentation of antidepressant treatment in T4-replaced thyroid patients. J Clin Psychiatry 1992 Jan;53(1):16-8.

Does thyroid supplementation accelerate tricyclic antidepressant response?” Six studies were (reviewed). All were conducted with triiodothyronine (T3) and a tricyclic antidepressant. Five of the six studies found T3 to be significantly more effective than placebo in accelerating clinical response?.the effects of T3 (seemed to be greater in women).

Altshuler LL, et al. Does thyroid supplementation accelerate tricyclic antidepressant response? A review and meta-analysis of the literature. Am J Psychiatry 2001 Oct;158(10):1617-22.

?we concluded that Free T3 and TSH levels were significantly lower in the depressed group?and that Free T4 was slightly but not significantly increased in the depressed group. Free T3 decrease and the slight Free T4 increase in depression may be the consequence of (inadequate conversion of T4) into Free T3. Its link with intensity and polarity of depression suggests that it can be considered as a biological marker of this disease.

De Mendonca Lima CA, et al. [Thyroid function in depressed patients]. Encephale 1996 Mar-Apr;22(2):85-94.