Piperazine-substituted benzothiophenes for treatment of mental disorders

A method for treating schizophrenia comprising administering a heterocyclic compound represented by the formula (I) or a salt thereof to a human or animal:

• wherein ring Q represented by
• represents
• wherein
• represents —NH—CH2—, —N═CH—, —CH2—NH— or —CH═N—;
• and
• the carbon-carbon bond
• between the 3-position and 4-position of the heterocyclic skeleton containing Z and Y represents a single bond or a double bond;
• the ring Q may have at least one substituent selected from the group consisting of a lower alkyl group, a lower alkenyl group, a lower alkynyl group, a hydroxy group, a lower alkoxy group, a halogenated lower alkyl group, an aryl group, an aryl lower alkyl group, an aryl lower alkoxy group, an arylcarbonyl group, a lower alkenyloxy group, a lower alkanoyl group, a lower alkanoyloxy group, a cycloalkyl group, a cycloalkyl lower alkyl group, a halogen atom, a carbamoyl group which may have a lower alkyl group, a carboxy group, a lower alkoxycarbonyl group, an amino group which may have a lower alkanoyl group, a nitro group, a hydroxy lower alkyl group, an amino lower alkyl group which may have a lower alkyl group, a thienyl group, a saturated 3- to 8-membered heteromonocyclic group containing 1 to 2 nitrogen atoms-substituted lower alkyl group and an oxo group;
• R2 represents a hydrogen atom or a lower alkyl group;
• and
• A represents —O-A1- (wherein A1 represents an alkylene group which may be substituted with a hydroxy group (wherein the one oxygen atom may replace a carbon of the alkylene chain) or a lower alkenylene group) or a lower alkylene group;
• provided that when A represents a lower alkylene group, the ring Q represents a bicyclic group selected from the group consisting of:
• wherein the carbon-carbon-bond
• represents a single bond or a double bond.