The present invention provides the use of a compound of formula (I); wherein: n is 0, 1, 2, or 3, the bonds shown with the dashed lines are saturated, or unsaturated with one or more double bonds; R, and R'are independently selected from hydrogen, alkyl, aryl, --OH, --OR'' --SH, --SR''--NH, --NHR'', .dbd.O, .dbd.NH, .dbd.NR''; R'' is independently selected from alkyl, aryl, in the preparation of a medicament for the treatment of a disease requiring a GSK-3 inhibitor. Also provided is a compound of formula (II); wherein n is 0, 1, 2, or 3 the bonds shown with the dashed lines are saturated, or unsaturated with one or more double bonds. Also provided are methods of treating chronic neurodegenerative conditions.