The invention relates to novel 1,6-disubstituted pyrazolopyrimidinones, Formula (I) with is a mono-, bi- or tri-cyclic heterocyclyl group, the ring members of which are carbon atoms and at least 1, preferably 1, 2 or 3, heteroatom(s), which are selected from the group of nitrogen, oxygen and sulphur, which is in the form of —S(O)r— with r being 0, 1 or 2, and—said heterocyclyl group is or comprises 1 non-aromatic, saturated, or partly unsaturated monocyclic ring which comprises at least 1 heteroatom as ring member and—said heterocyclyl group is bound to the scaffold by said 1 non-aromatic, saturated, or partly unsaturated monocyclic ring which comprises at least 1 heteroatom as ring member. According to one aspect of the invention the new compounds are for the manufacture of medicaments, in particular medicaments for the treatment of conditions concerning deficits in perception, concentration, learning or memory. The new compounds are also for the manufacture of medicaments for the treatment of Alzheimer's disease.