Pharmaceutical composition for treating alzheimer's disease

A method for treating Alzheimer's disease, comprising:

• administering a composition in an amount effective for treating Alzheimer's disease to a subject in need thereof,
• wherein the composition comprises a compound represented by the general formula (I):
• wherein ring A is an optionally substituted carbocyclic group or an optionally substituted heterocyclic group,
• wherein Alk1 is lower alkylene or lower alkenylene;
• R0 is a hydrogen atom, lower alkyl, or acyl;
• X is S or O;
• R2a and R2b are each independently a hydrogen atom, hydroxy, optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted amino, optionally substituted amidino, optionally substituted acyl, optionally substituted carbamoyl, optionally substituted carbamoylcarbonyl, optionally substituted lower alkylsulfonyl, optionally substituted arylsulfonyl, an optionally substituted carbocyclic group, or an optionally substituted heterocyclic group;
• R3a, R3b, R4a, and R4b are each independently a hydrogen atom, halogen, hydroxy, optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted acyl, carboxy, optionally substituted lower alkoxycarbonyl, optionally substituted amino, optionally substituted carbamoyl, an optionally substituted carbocyclic group, or an optionally substituted heterocyclic group;
• n and m are each independently an integer of 0 to 3;
• n+m is 3;
• each R3a, each R3b, each R4a, and each R4b may be independently different;
• R5 is a hydrogen atom, optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted lower alkynyl, an optionally substituted carbocyclic group, or an optionally substituted heterocyclic group;
• R5 and ring A can be taken together to form
• wherein R5a and R5b are each independently a hydrogen atom or lower alkyl;
• s is an integer of 1 to 4;
• and
• each R5a and each R5b may be different,
• its pharmaceutically acceptable salt, or a solvate thereof as an active ingredient.