Abstract: This invention relates to methods of treating Alzheimer's disease or symptoms thereof, and amnesic mild cognitive impairment or symptoms thereof. Methods of the invention include administering a therapeutically effective amount of tissue kallikrein, variants or active fragments thereof. The invention further relates to uses of tissue kallikrein or a variant or active fragment thereof for the digesting or cleaving amyloid and the treatment of conditions benefiting from the digestion or cleavage of amyloid. The invention further relates to pharmaceutical compositions comprising a therapeutically effective amount of tissue kallikrein, variants or active fragments thereof formulated for oral or intranasal administration.