Could Insulin Be A Factor In The Development Of Dementia? Five Ways To Make Insulin More Sensitive
Written by: Dr. Romi Fung, Executive Contributor
Executive Contributors at Brainz Magazine are handpicked and invited to contribute because of their knowledge and valuable insight within their area of expertise.
Type 3 Diabetes? Ever heard that Alzheimer’s disease has coined the term, ‘Type 3 Diabetes?’ There is a growing number of statistics that show this correlation. 40–60% of people who have been living with diabetes for 5 years or more were found to be diagnosed with dementia compared to those who do not have diabetes (Pal et al., 2018), as well as the use of oral hypoglycemic agents are linked to a lower risk of developing dementia (Pal et al., 2018).
It is conventional practice in diabetics to monitor and manage high blood sugar levels using pharmaceuticals that involve hypoglycemic (blood sugar lowering) effects. However, there is not enough consideration for insulin, the hormone responsible for controlling blood sugar levels and signals cells to take up glucose for energy.
What is the difference between diabetes and insulin resistance? Aren’t they the same?
Diabetes is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both (American Diabetes Association, 2010). While diabetes is collectively defined as a disease that results in high blood sugar, insulin resistance refers to a specific contributing factor of the definition of diabetes.
Insulin is a hormone made by the pancreas to facilitate glucose to enter cells in our muscles, fat, and liver and to be used for energy. Insulin resistance is what happens when these cells do not respond to insulin. As a result, the body would attempt to make this more efficient by producing more insulin to maintain blood sugar levels. Your blood sugar levels may be shown to be maintained, but your insulin levels may be very high.
There is no exact timeframe from developing insulin resistance to being diagnosed with diabetes, as there are many factors; insulin resistance is not black and white. Over time, insulin may not be sensitive enough, leading to hyperglycemia. That is when one may be diagnosed with diabetes.
Having insulin resistance does not mean you have diabetes. However, people with diabetes are insulin resistant.
What effects does insulin resistance have on the brain?
Insulin resistance is not only exclusive to muscle and fat tissue; the brains of insulin-resistant individuals also become insulin resistant. Brain insulin resistance can manifest as impaired central regulation of nutrient partitioning, cognitive and mood dysfunction, brain-specific neuropathology and neurodegeneration (Arnold et al., 2018).
The hippocampus, a brain region key to memory and learning, was found to present particularly high levels of insulin receptors, suggesting that insulin could play a role in synaptic plasticity mechanisms and memory formation in rodents and humans (De Felice & Benedict, 2015). With insulin resistance, this process of connection building and memory becomes impaired.
Insulin also plays a critical role in the formation of amyloid plaques, and insulin is also involved in the phosphorylation of tau, which leads to neurofibrillary tangles (van Oijen et al., 2008). Higher insulin levels were associated with a faster decline in the telephone interview for cognitive status (TICS) and verbal memory (van Oijen et al., 2008). This could signify that higher insulin levels can predispose one to form more plaques.
What are the signs of early insulin resistance when blood sugar levels appear normal?
A common symptom of insulin resistance is becoming extremely sleepy after eating. This is due to the effects of the sugar and insulin surge on the brain’s neurotransmitters and the high energy demand of converting sugar into fat.
A blood test can be written by a physician, medical doctor, or naturopathic doctor to assess fasting insulin and insulin tolerance. Using the lab value of fasting insulin, an insulin resistance calculator called HOMA-IR (Homeostatic Model Assessment for Insulin Resistance) determines how insulin resistant one is.
What if I was tested and have insulin resistance?
There are strategies to make insulin more sensitive; the key here is to catch it and act upon it earlier for a better prognosis.
Physical exercise remains important. Aim for 30-60 minutes of moderate to intense physical activity for at least 3-5 days a week. Incorporate both aerobic and anaerobic activities such as weights and resistance training. HIIT training is amazing!
Sleep is also a cornerstone in health and insulin resistance. Ensure you are getting 7-9 hours of good quality sleep. If sleep is affected, part of the work will have to include sleep maintenance and hygiene interventions. You cannot out-supplement or out-exercise poor sleep.
Keeping blood sugar levels maintained throughout the day. Ensure your meals have a good portion of protein, fat and/or fibre to prevent any blood sugar spikes that can contribute to insulin resistance. I get patients to try and get 5g of fibre at each meal and/or a couple of servings of protein (the size of a deck of cards is approximately a serving of protein). Avoid simple sugars and carbohydrates as much as possible!
Some supplements and herbs can support insulin and blood sugar regulation. Some of my favourites include berberine, magnesium, and resveratrol. Consult with your medical professional for optimal dosages and potential interactions with current medications and other supplementation.
Stress management is also underappreciated for blood sugar regulation. Cortisol is a stress hormone that facilitates glucose release and can exacerbate blood sugar maintenance. Cortisol has been found to contribute to the reduction in insulin sensitivity (Adam et al., 2010). Consider deep breathing, mindfulness, a brisk walk (physical exercise above!) and bodywork!
As these are general guidelines, it is recommended that you seek a medical professional to work with you with specific interventions, supplementations and/or prescriptive medications. Making the simplest but consistent habit of working towards insulin sensitivity one step at a time builds up.
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Dr. Romi Fung, ND, M.Sc, Ph.D (cand.), Executive Contributor Brainz Magazine
Dr. Romi Fung is a naturopathic physician practicing in Richmond, BC, Canada with a special focus in dementia and cognitive health. Dr. Fung works with patients living with cognitive decline and dementia by augmenting their brain's environment. He believes there is more to dementia than just working primarily with the brain; several metabolic and biochemical factors affecting our brain emerge from the body. Dr. Fung takes a comprehensive approach in working with his patients, from screening for inflammation, insulin resistance, and imbalanced hormones – all of which contribute significantly to our brain health, to interventions, including lifestyle coaching and clinical nutrition.
References:
Adam, T. C., Hasson, R. E., Ventura, E. E., Toledo-Corral, C., Le, K. A., Mahurkar, S., Lane, C. J., Weigensberg, M. J., & Goran, M. I. (2010). Cortisol is negatively associated with insulin sensitivity in overweight Latino youth. The Journal of clinical endocrinology and metabolism, 95(10), 4729–4735. https://doi.org/10.1210/jc.2010-0322
American Diabetes Association (2010). Diagnosis and classification of diabetes mellitus. Diabetes care, 33 Suppl 1(Suppl 1), S62–S69. https://doi.org/10.2337/dc10-S062
Arnold, S. E., Arvanitakis, Z., Macauley-Rambach, S. L., Koenig, A. M., Wang, H. Y., Ahima, R. S., Craft, S., Gandy, S., Buettner, C., Stoeckel, L. E., Holtzman, D. M., & Nathan, D. M. (2018). Brain insulin resistance in type 2 diabetes and Alzheimer disease: concepts and conundrums. Nature reviews. Neurology, 14(3), 168–181. https://doi.org/10.1038/nrneurol.2017.185
De Felice, F. & Benedict, C. (2015). A Key Role of Insulin Receptors in Memory. Diabetes 64 (11): 3653–3655. https://doi.org/10.2337/dbi15-0011
Pal, K., Mukadam, N., Petersen, I., & Cooper, C. (2018). Mild cognitive impairment and progression to dementia in people with diabetes, prediabetes and metabolic syndrome: a systematic review and meta-analysis. Social psychiatry and psychiatric epidemiology, 53(11), 1149–1160. https://doi.org/10.1007/s00127-018-1581-3
