Brain health: Sugars role in dementia

Written By Sian Barlow

Today the Guardian released a piece on protein markers in the blood which may predict potential for dementia. It talks about markers and the potential for drug use sooner, however, it doesn’t talk about what we can do without drugs to reduce our risk.

One big factor is sugar. The impact of raised blood sugar on weight and diabetes risk is pretty well known. The effect blood sugar has on cognition is probably less well-known. You might experience brain fog or slower cognition when you’re hungry but do you know how much sugar impacts your brain health long term? That it been linked to a significant increase in the risk of dementia? 

55 million people have dementia worldwide (1), with 1 million people in the UK currently suffering and 790 diagnoses every day! (2) 

Dementia is a collective term for the syndrome created by neuronal decline and brain damage which leads to cognitive impairment and Alzheimer’s is one of the most common forms (1). It’s normal for our brains to shrink as we age, but the speed of that shrinkage is what has been linked to cognitive impairment. 

Yearly brain shrinkage

  • Normal ageing = ~0.5% per year

  • Mild cognitive impairment = ~1% per year

  • Alzheimer’s Disease = ~2.5% per year 

A 15mg increase of HDL (“good” cholesterol) has been linked to a decreased AD risk, whereas the same 15mg increase in glucose has been associated with increased AD risk (4).

The role of insulin

Insulin resistance occurs when the body's cells become less responsive to the hormone insulin, which is responsible for regulating blood sugar levels. This can lead to impairments in glucose metabolism and energy production in the brain, which are critical for normal cognitive function.

Research has shown that insulin resistance may play a role in the development of cognitive decline and dementia, including Alzheimer's disease (3). When brain cells become insulin resistant, they may not be able to effectively utilise glucose for energy, leading to a reduced ability to form and retrieve memories.

Additionally, insulin resistance can trigger inflammation and oxidative stress in the brain, which can damage neurons and contribute to the development of neurodegenerative diseases. (3,4,5)

Studies have also found that individuals with type 2 diabetes, which is characterized by insulin resistance, has been associated with more rapid brain shrinkage and almost doubles the risk for dementia. (6,7,8)

Sugar and the brain

Carbohydrates break down to glucose which enters our blood. Type, form and food combinations can impact the speed it raises our blood sugar and our insulin response. High sugar and carbohydrate intake means the potential for faster and higher sugar spikes and more work for insulin.

Fructose in particular has been found to promote neuroinflammation and oxidation and damage mitochondrial function, leading to reduced brain energy, all things we don’t want to happen in our brains.

Fructose also inhibits autophagy, which helps clean up and remove damaged mitochondria to regenerate new, healthier cells. So it both damages mitochondria and prevents regeneration. 

Sugar also produces something called Advanced Glycation Endpoints (AGEs), which oxidise proteins, form clumps in the brain, and drain Vitamin C and E, two very important antioxidant nutrients.

If we reduce our blood sugar spikes and manage our overall blood sugar levels, we can improve insulin sensitivity, and positively influence our risk of cognitive decline and dementia. (9,10)

What can you do to support your brain health?

  • Ensure a balanced diet, low in refined carbohydrates and sugar, high in good protein, healthy fats and fibre

  • Ensure a good vitamin B status. This has been found to play an important role in brain health. You can get this tested with various testing companies but make sure you have someone to interpret them in the context of your lifestyle and diet.

  • Check your homocysteine levels - this is a bi-product of an important process called methylation and has been linked to multiple chronic diseases, including heart disease, cancer and AD

  • Ensure a good intake of omega-3 fish (or Algae) oil - make sure your vitamin B status is good to get the optimal effect, especially folate (B9 levels) (10). 

  • Stimulate your brain - learning, language social interactions, brain training, exercise and developing new skills have all been shown to improve cognition and reduce decline (11)

  • Make sure you’re getting good quality sleep - less than 7 and more than 8 starts to increase the risk of dementia (12)

  • Manage stress - increased cortisol has been found to induce hippocampal atrophy, impacting brain function (13) so establish helpful ways to reduce and manage stress.

Wondering how your cognition is? Test it with this Cognitive Function test

 


References

  1. WHO https://www.who.int/news-room/fact-sheets/detail/dementia

  2. Alzheimer’s Society https://www.alzheimers.org.uk/

  3. Schrijvers, E. M., Witteman, J. C., Sijbrands, E. J., Hofman, A., Koudstaal, P. J., & Breteler, M. M. (2010). Insulin metabolism and the risk of Alzheimer disease: the Rotterdam Study. Neurology, 75(22), 1982–1987. 

  4. Zhang X, Tong T, Chang A, Ang TFA, Tao Q, Auerbach S, Devine S, Qiu WQ, Mez J, Massaro J, Lunetta KL, Au R, Farrer LA. Midlife lipid and glucose levels are associated with Alzheimer's disease. Alzheimers Dement. 2023 Jan;19(1):181-193.

  5. Abbatecola AM, Paolisso G, Lamponi M, Bandinelli S, Lauretani F, Launer L, Ferrucci L. Insulin resistance and executive dysfunction in older persons. J Am Geriatr Soc. 2004 Oct;52(10):1713-8. doi: 10.1111/j.1532-5415.2004.52466.x. PMID: 15450050.

  6. Ye X, Gao X, Scott T, Tucker KL. Habitual sugar intake and cognitive function among middle-aged and older Puerto Ricans without diabetes. Br J Nutr. 2011 Nov;106(9):1423-32.

  7. Taylor MK, Sullivan DK, Swerdlow RH, Vidoni ED, Morris JK, Mahnken JD, Burns JM. A high-glycemic diet is associated with cerebral amyloid burden in cognitively normal older adults. Am J Clin Nutr. 2017 Dec;106(6):1463-1470.

  8. Arvanitakis Z, Wilson RS, Bienias JL, Evans DA, Bennett DA. Diabetes mellitus and risk of Alzheimer disease and decline in cognitive function. Arch Neurol. 2004 May;61(5):661-6.

  9. Yaffe K, Blackwell T, Kanaya AM, Davidowitz N, Barrett-Connor E, Krueger K. Diabetes, impaired fasting glucose, and development of cognitive impairment in older women. Neurology [Internet]. 2004 Aug 24 [cited 2022 Mar 16];63(4):658–63. Available from: https://n.neurology.org/content/63/4/658

  10. Samaras K, Lutgers HL, Kochan NA, Crawford JD, Campbell LV, Wen W, et al. The impact of glucose disorders on cognition and brain volumes in the elderly: the Sydney Memory and Ageing Study. AGE [Internet]. 2014 Jan 9 [cited 2022 Aug 5];36(2):977–93. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4039246/

  11. Luchsinger JA, Tang M-X ., Shea S, Mayeux R. Hyperinsulinemia and risk of Alzheimer disease. Neurology. 2004 Oct 11;63(7):1187–92.

  12. Xu WL, von Strauss E, Qiu CX, Winblad B, Fratiglioni L. Uncontrolled diabetes increases the risk of Alzheimer’s disease: a population-based cohort study. Diabetologia. 2009 Mar 12;52(6):1031–9.

  13. Fairbairn P, Dyall SC, Tsofliou F. The effects of multi-nutrient formulas containing a combination of n-3 PUFA and B vitamins on cognition in the older adult: a systematic review and meta-analysis. Br J Nutr. 2023 Feb 14;129(3):428-441.

  14. Turknett J, Wood TR. Demand Coupling Drives Neurodegeneration: A Model of Age-Related Cognitive Decline and Dementia. Cells. 2022; 11(18):2789. https://doi.org/10.3390/cells11182789

  15. Bubu et al., Sleep. 2017; Sabia et al., Nature Communications 2021

  16. Sabia, Séverine, Fayosse A., Dumurgier J., T. van Hees V., Paquet C., Sommerlad A., Kivimäki M., Dugravot A., Singh-Manoux A. (2021). “Association of Sleep Duration in Middle and Old Age with Incidence of Dementia.” Nature Communications 12 (1): 2289.

Sian Barlow
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