The present invention relates to a composition comprising a lithium salt of an N-substituted glycine compound and a carrier, wherein the lithium salt of the N-substituted glycine compound is of Formula (I): in which R1, R2, and R3 each are independently hydrogen, alkyl, alkenyl, alkynyl, aralkyl, carbocyclyl, aryl, or heteroaryl, or one of R1, R2, and R3 is absent. Also provided in the present invention is a method of mitigating at least one symptom of a neuropsychiatric disorder, comprising administering to a subject in need thereof the lithium salt of an N-substituted glycine compound of Formula (I).