bicyclic pyridine and piperazine compounds having affinity for the 5-HT6 receptor.

A compound according to formula ** ** and a salt, solvate or hydrate thereof, wherein: R1, R2, R3 and R4 are independently selected from the group consisting of H, halo, OH, C1-6 alkyl , C1-6 alkoxy, C2-6 alkenyl, C2-6 alkynyl, C3-7 cycloalkyl, C4-7 cycloalkenyl, C3-7 cycloalkoxy, C3-7 cycloalkylthio, C1-6 halo- substituted alkyl, C1-6 alkylthio, alkanoyl C3-7, C2-7 alkanoyloxy, nitro, cyano, optionally substituted phenyl, optionally substituted furanyl, optionally substituted thienyl, optionally substituted phenyloxy, SO2NR8R9, CH2SO2NR8R9, CO2R10, NHC (NR12) R11, C (NR13) NR14R15, C (O ) R16, OC (O) R16, SCF3, SO2CF3, formyl, CF3 and CF3O; R5 is selected from the group consisting of SO2Ar, C (O) Ar, CH 2 Ar and AT.