Cyproterone acetate can cause depression in some people and is usually avoided in people with prior depressive symptoms. Estrogen, on the other hand, is known to improve mood. Too little T or E in the body can also cause depression.
J Clin Endocrinol Metab. 2012 Dec;97(12):4422-8.
"Of the antiandrogens studied, only cyproterone acetate was significantly associated with depression"
"Cyproterone acetate use is statistically more likely to cause depression than the other antiandrogen types used in this study. These results are consistent with previous studies using cyproterone acetate to treat hirsutism (11–13). It is, however, the first time this has been reported in transwomen. The incidence of depression was much lower in those using GnRH analogs, which is consistent with the findings of Dittrich et al. in 2005 (14), who found that depression was not a significant problem in transwomen treated with GnRH analogs."
European Journal of Endocrinology (2011) 164 635–642
"Depressive mood changes have been reported in cyproterone acetate use"
Basson RJ. Towards optimal hormonal treatment of male to female gender identity disorder. J Sex Reprod Med 2001;1:45–51.
"a high incidence of depression with its associated increased risk of suicide, for which persons with GID are already at increased risk, is reported by Asscheman et al (7) who routinely use CPA."
Metabolism. 1989 Sep;38(9):869-73.
« Combined treatment with estrogen and cyproterone acetate in 303 male-to-female transsexuals was associated with (...)depressive mood changes (15-fold)"
Acta Endocrinol (Copenh). 1979 Jul;91(3):545-52.
« One daily dose of either * cyproterone acetate (CA) was administered to 2 groups of 4 fertile men for 6 months."
"Three subjects who began the study were withdrawn because of depressive mood changes (2) and weakness combined with dizziness (1)."