A compound of formula IA or a pharmaceutically active salt thereof, a stereoisomeric form, including an individual diastereoisomer or enantiomer of the compound of formula as well as a racemic or non-racemic mixture thereof; wherein G 1 is lower alkyl; lower alkyl substituted by one or more halogens; tetrahydropyran-4-yl; phenethyl; phenethyl substituted by one or more halogens; phenoxymethyl; phenoxymethyl substituted by one or more halogens; benzyloxy-ethyl; benzyloxy-ethyl substituted by one or more halogens; or is -NR 2 R 3; R 2 is hydrogen or lower alkyl; R 3 is lower alkyl, tetrahydropyran-4-yl -CH 2 -cycloalkyl or cycloalkyl optionally substituted by lower alkyl substituted by one or more halogens; or R 2 and R 3 form together with the N-atom to which they are attached a heterocycloalkyl group with 4 or 5 carbon atoms, which is optionally substituted by one or more substituents selected from halogen or lower alkyl substituted by one or more halogens; X is -CH 2 - or -(CH 2) 2 -; Ar is phenyl or pyridinyl; R 4 is halogen; lower alkyl; lower alkyl substituted by one or more halogens; or lower alkoxy; n is 1 or 2; wherein, the term "lower alkyl" denotes a saturated straight- or branched-chain group containing from 1 to 7 carbon atoms; the term "lower alkyl substituted by halogen" denotes an alkyl group as defined above, wherein at least one hydrogen atom is replaced by halogen; the term "lower alkoxy" denotes a group wherein the alkyl residue is as defined above and which is attached via an oxygen atom; or wherein said compound is: 1-(3-Cyclohexyl-[1,2,4]thiadiazol-5-yl)-4-[2-(4-methoxy-phenyl)-ethyl]-piperazine; 1-(3-Cyclohexyl-[l,2,4]thiadiazol-5-yl)-4-[2-(3-methoxy-phenyl)-ethyl]-piperazine; 1-(3-Cyclopropyl-[1,2,4]thiadiazol-5-yl)-4-[2-(4-methoxy-phenyl)-ethyl]-piperazine; 1-(3-Cyclopropyl-[1,2,4]thiadiazol-5-yl)-4-[2-(3-methoxy-phenyl)-ethyl]-piperazine with the proviso that said compound is not: - 5-(4-(3-fluorobenzyl)piperazin-1-yl)-3-methyl-1,2,4-thiadiazole. G 1 is lower alkyl; lower alkyl substituted by one or more halogens; tetrahydropyran-4-yl; phenethyl; phenethyl substituted by one or more halogens; phenoxymethyl; phenoxymethyl substituted by one or more halogens; benzyloxy-ethyl; benzyloxy-ethyl substituted by one or more halogens; or is -NR 2 R 3; R 2 is hydrogen or lower alkyl; R 3 is lower alkyl, tetrahydropyran-4-yl -CH 2 -cycloalkyl or cycloalkyl optionally substituted by lower alkyl substituted by one or more halogens; or R 2 and R 3 form together with the N-atom to which they are attached a heterocycloalkyl group with 4 or 5 carbon atoms, which is optionally substituted by one or more substituents selected from halogen or lower alkyl substituted by one or more halogens; X is -CH 2 - or -(CH 2) 2 -; Ar is phenyl or pyridinyl; R 4 is halogen; lower alkyl; lower alkyl substituted by one or more halogens; or lower alkoxy; n is 1 or 2; the term "lower alkyl" denotes a saturated straight- or branched-chain group containing from 1 to 7 carbon atoms; the term "lower alkyl substituted by halogen" denotes an alkyl group as defined above, wherein at least one hydrogen atom is replaced by halogen; the term "lower alkoxy" denotes a group wherein the alkyl residue is as defined above and which is attached via an oxygen atom; 1-(3-Cyclohexyl-[1,2,4]thiadiazol-5-yl)-4-[2-(4-methoxy-phenyl)-ethyl]-piperazine; 1-(3-Cyclohexyl-[l,2,4]thiadiazol-5-yl)-4-[2-(3-methoxy-phenyl)-ethyl]-piperazine; 1-(3-Cyclopropyl-[1,2,4]thiadiazol-5-yl)-4-[2-(4-methoxy-phenyl)-ethyl]-piperazine; 1-(3-Cyclopropyl-[1,2,4]thiadiazol-5-yl)-4-[2-(3-methoxy-phenyl)-ethyl]-piperazine with the proviso that said compound is not: - 5-(4-(3-fluorobenzyl)piperazin-1-yl)-3-methyl-1,2,4-thiadiazole. - 5-(4-(3-fluorobenzyl)piperazin-1-yl)-3-methyl-1,2,4-thiadiazole.