1. A pharmaceutical composition for treating schizophrenia in a mammalian subject comprising an effective amount of a fatty acid represented by the formula (I): where: L, M and N are hydrogen, hydroxy, halogen, lower alkyl, hydroxy (lower) alkyl, lower alkanoyloxy or oxo, wherein the five-membered ring may have at least one double bond A represents -CHili -CHOH, -COCHOH, -COOH or its functional derivative B is single bond, -CH-CH-, -CH = CH- , -C≡C-, -CH-CH-CH-, -CH = CH-CH-, -CH-CH = CH-, -C≡C-CH- or -CH-C≡C- Z oznachaetili single bond, where r and is hydrogen, hydroxy, halogen, lower alkyl, lower alkoxy or hydroxy (lower) alkyl, wherein r and can mean Rne hydroxy and lower alkoxy at the same time Zoznachayut Z and oxygen, nitrogen or sulfur R and Roznachayut optionally substituted lower alkyl, which are optionally joined together to form lower alkylene Roznachaet saturated or unsaturated divalent residue of a lower or medium aliphatic hydrocarbon, which is unsubstituted or substituted by halogen, lower alkyl, hydroxy, oxo, aryl or heterocyclic group, and at least one carbon atom in the aliphatic hydrocarbon is optionally substituted by oxygen, nitrogen or sulfur iRa means a saturated or unsaturated lower or medium residue of an aliphatic hydrocarbon which is unsubstituted or substituted by halogen, oxo, hydroxy, lower alkyl, lower alkoxy, lower alkanoyloxy, lower cycloalkyl, lower cycloalkyloxy, aryl, aryloxy, heterocyclic group or heterocyclic oxy group lower alkoxy lower alkanoyloxy lower cycloalkyl lower cycloalkyloxy aryl
