The invention relates to therapeutic uses of a
dihydrospiro-[cycloalkyl]-pyrimidone derivative represented by formula
(I) or a salt thereof: ##STR00001## wherein X, Y, R1, R2, R3, m, n, p
and q are as described herein. Specifically, the invention relates to a
medicament comprising the said derivative or a salt thereof as an active
ingredient which is used for preventive and/or therapeutic treatment of a
neurodegenerative disease caused by abnormal activity of GSK3.beta., such
as Alzheimer disease.