Methods are provided herein for treating mania in mood disorders and other neurological diseases or disorders. The methods provided herein comprise administering a VMAT2 inhibitor to a subject in need thereof. A VMAT2 inhibitor useful in the methods provided herein includes (S)-2-Amino-3-methyl-butyric acid (2R,3R,11bR)-3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-pyrido[2,1-a]isoquinolin-2-yl ester.