This disclosure relates to a method of treating a disease selected from the group consisting of affective disorders, depression, major depressive disorder, anxiety, general anxiety disorder, social anxiety disorder, obsessive compulsive disorder, panic disorder, and panic attacks. The method includes administering a therapeutically effective amount of Compound I or a pharmaceutically acceptable salt thereof to a patient in need thereof, in which Compound I is 1-[2-(2,4-dimethylphenylsulfanyl)-phenyl]piperazine.