Insulin administered via the nasal passages slowed or stabilized mental functioning and functional abilities in a pilot study of people with Alzheimer disease and mild cognitive impairment, according to Seattle-based investigators.
As you probably know, dementia is a huge problem for our aging population, and Alzheimers is the most common form of dementia. The Mediterranean diet is associated with lower risk of mild cognitive impairment and has long been linked to lower risk of dementia as well as slower mental decline in existing Alzheimer dementia patients. The Mediterranean diet also seems to prolong life in Alzheimer patients. So I’m always interested in ways to prevent and treat Alzheimers. Mild cognitive impairment is often a precursor to Alzhiemer disease.
The study involved 104 non-diabetic participants with Alzheimer disease (40) or amnestic mild cognitive impairment (64). They were randomly assigned to one of three groups: placebo (control group), nasal insulin 20 IU twice daily, or nasal insulin 40 IU twice daily.
Insulin was delivered through a ViaNase device which releases the insulin in to a chamber covering the nose; the participant breathes regularly for two minutes to pick up the dose. This insulin goes directly to the central nervous system without affecting blood insulin levels or blood sugar levels.
Mental and functional abilities (for example, activities of daily living) were measured at baseline, then again 2, 4, and six months later. Some of the participants (23) underwent lumbar puncture (for dementia biomarker analysis) and PET brain scans (18).
This was a well-designed pilot study.
Nasal insulin was well-tolerated. It’s not commercially available in the U.S.
Regarding the placebo group, I was surprised that the researchers could document mental and functional deterioration over this relatively short-term study (4–6 months). I’m impressed with the need to treat age-related cognitive decline early and aggressively, when we have something that works.
How would nasal insulin work? We don’t know for sure, but it seems to relate to insulin’s effect on
- the ability of neurons (brain cells) to communicate with each other through synapses
- modulaton of blood sugar metabolism in the hippocampus and other brain areas
- facilitation of memory
- ß-amyloid peptide
In case you’re wondering, standard subcutaneous injections of insulin can’t be used in studies like this because of the risk of low blood sugar.
I agree wholeheartedly with study authors that “these promising results provide an impetus for longer-term trials of intranasal insulin therapy in adults with amnestic mild cognitive impairment or Alzheimers disease.”
Psychiatrist Emily Deans blogged about this study at Evolutionary Psychiatry September 21, 2001. Please see her cogent remarks.
Reference: Craft, S., Baker, L., Montine, T., Minoshima, S., Watson, G., Claxton, A., Arbuckle, M., Callaghan, M., Tsai, E., Plymate, S., Green, P., Leverenz, J., Cross, D., & Gerton, B. (2011). Intranasal Insulin Therapy for Alzheimer Disease and Amnestic Mild Cognitive Impairment: A Pilot Clinical Trial Archives of Neurology DOI: 10.1001/archneurol.2011.233