Abstract: A formulation for treating neurodegenerative diseases comprising a combination of rapamycin and metformin in a molar ratio of about 20:1, 10:1, 5:1, 4:1, 3:1, or 1:1. A method of treating neurodegenerative diseases comprising administering the formulation comprising a combination of rapamycin and metformin in a molar ratio of about 20:1, 10:1, 5:1, 4:1, 3:1, or 1:1.