This invention is directed to a method of treating depression in a subject, comprising the step of administering a therapeutically effective amount of a conventional antidepressant and, in addition, administering to the subject a therapeutically effective amount of a compound of Formula (I) or a pharmaceutically acceptable salt or ester thereof wherein Rx is a member Rx selected from the group consisting of hydrogen, lower alkyl of 1 to 8 carbon atoms, halogen selected from F, Cl, Br and I, alkoxy containing 1 to 3 carbon atoms, nitro, hydroxy, trifluoromethyl, and thioalkoxy containing 1 to 3 carbon atoms x is an integer of 1 to 3, with the proviso that R may be the same or different when x is 2 or 3 R1 and R2 can be the same or different from each other and are independently selected from the group consisting of hydrogen, lower alkyl of 1 to 8 carbon atoms, aryl, arylalkyl, cycloalkyl of 3 to 7 carbon atoms R1 and R2 can be joined to form a 5 to 7-membered heterocycle substituted with a member selected from the group consisting of hydrogen, alkyl, and aryl groups, wherein the cyclic compound can comprise 1 to 2 nitrogen atoms and 0 to 1 oxygen atom, wherein the nitrogen atoms are not directly connected with each other or with the oxygen atom.
