The importance of the Klotho protein in antidepressant therapy in geriatric patients with severe depression was also confirmed by Hoyer et al., who observed higher levels of Klotho, but only in the cerebrospinal fluid (not in serum), which was positively correlated with the number of single electroconvulsive therapy (ECT) sessions [112]. The gene discussed is KL; the disease is major depressive disorder.