As reported by Prien (see p 847), two United States committees concluded in 1975 that lithium is prophylactically efficacious, ie, significantly better than placebo, in recurrent bipolar affective illness. The committees felt, however, that they could not recommend the prophylactic use of lithium in recurrent unipolar affective illness (1) because there is uncertainty as to what a unipolar disorder represents and (2) because the evidence for the efficacy of lithium in this disease type is based on a relatively small number of patients.
With the first reason given, the committees more or less acknowledge that lack of trust in the psychiatrists' ability to diagnose recurrent unipolar affective illness played a role in their decision. I have no comment to offer on this. As regards the second reason: It might be worth comparing the evidence now available for prophylactic efficacy of lithium and of cyclic antidepressants in unipolar affective illness. Use
Schou M. Lithium as a Prophylactic Agent in Unipolar Affective IllnessComparison With Cyclic Antidepressants. Arch Gen Psychiatry. 1979;36(8):849-851. doi:10.1001/archpsyc.1979.01780080023006