In a recent double-blind study of 104 adults with mild cognitive impairment or mild-to-moderate Alzheimer's disease, Craft and colleagues [229] randomized participants to receive 4 months of intranasal delivery of (1) 20 international units of insulin a day, (2) 40 international units of insulin a day, or (3) a placebo. This evidence concerns the gene INS and early-onset autosomal dominant Alzheimer disease.