Measurement of Insulin Levels in Cerebral Spinal Fluid (CSF) of Healthy Adults After a Single Intranasal Dose

The purpose of this study is to find out whether insulin, a drug approved by the FDA for the treatment of diabetes mellitus, reaches the brain and spinal cord when delivered as a nasal spray (intranasally). Intranasal insulin has been shown to improve memory and mood in patients with mild cognitive impairment and dementia, but more evidence is needed to support the ability to effectively target the brain through intranasal routes. 12 healthy adults will be randomly assigned to receive a single dose of either 40 units ("low dose" group) or 80 units ("high dose" group) of insulin. Participants will undergo image-guided lumbar puncture (spinal tap) performed by a study radiologist. Samples of cerebrospinal fluid (a fluid surrounding the brain and spinal cord) and blood will be collected at 5 timepoints during the lumbar puncture: once prior to the administration of intranasal insulin, and again at 10, 20, 30, and 40 minutes after the dose is given. Samples will be tested to determine the level of insulin detected in the cerebrospinal fluid and blood at each time point. Results of this study will provide essential information about the ability of the SipNose device to effectively deliver insulin to the central nervous system of humans as measured in the cerebrospinal fluid.