Provided are a clinically applicable drug for radical cure of Alzheimer's disease (AD), and a drug for treating neurological diseases associated with axonal dysfunction other than AD, wherein the drug utilizes the mechanism of action of the AD radical cure therapy. The drugs are oral drugs, each comprising one or more compounds selected from diosgenin, a diosgenin derivative and a pharmaceutically acceptable salt thereof, the one or more compounds being suspended in an edible oil.