Does substitution of T4 with T3 plus T4 for T4 replacement improve depressive symptoms in patients with hypothyroidism?

Substitution of T4 with T3 for T4 replacement in patients with hypothyroidism was undertaken using a randomized placebo controlled study design. Forty individuals were included who had depressive symptoms on stable doses of levothyroxine. Combined T4 plus T3 did not have a significantly different effect on mood and well-being scores than did T4 alone.

Number of episodes and antidepressant response in major depression.

Current series of depression suggests that episodes of major depression sensitize a patient to further episodes so that the illness adopts a recurrent course. This suggested pathophysiological process may also lead to increased risk of treatment resistance and a chronic course of illness. This hypothesis has received little empirical support and, if correct, would suggest that greater number of episodes would lead to a decreased response to antidepressants.