SNIFF 120: Study of Nasal Insulin to Fight Forgetfulness (120 Days)

A growing body of evidence suggests that insulin plays a role in normal memory processes and that insulin abnormalities may contribute to cognitive and brain changes associated with Alzheimer's disease (AD). Interestingly, insulin administered to the nasal cavity is transported within a few minutes into the brain, but does not affect blood sugar or insulin levels. This study will consist of a randomized double-blind, placebo-controlled parallel group trial in which 90 participants with AD or MCI receive daily intranasal administrations of either insulin (10 or 20 IU twice a day for a total dose of 20 or 40 IU per day) or placebo (saline twice a day) for 4 months. The study will examine the effects of intranasal insulin administration on cognition, cerebral glucose metabolism, and β-amyloid (Aβ) in cerebrospinal fluid (CSF) and plasma, testing the hypothesis that daily intranasal insulin administration for 4 months will facilitate memory for adults with AD, and adults with mild cognitive impairment (MCI). A subset of participants will have the option to participate in 2 sub-studies: PET scans (prior to and at the end of treatment) to determine whether intranasal insulin increases cerebral glucose metabolism; lumbar punctures (LPs) before and at the end of treatment to determine effects of intranasal insulin administration on CSF Aβ levels.