Cognitive health is an extremely important topic and unfortunately something we often don’t talk much about until its almost too late.
Alzheimer’s dementia (AD) is the most prevalent form of dementia, representing about 60-80% of dementia cases. AD currently affects an estimated 6.2 million Americans (equal to about 1 in 9 individuals over 65 years of age). For Americans over 65 years of age, AD was the sixth leading cause of death; it is also reported as the fifth leading cause of total deaths in the US. 1 Additionally, Women represent every 2 out of 3 cases of dementia and have a prevalence rate of 37% compared to the prevalence of dementia in men at 24%. 2
With the increasing number of baby boomers over 65 years old, by the year 2050 the number of Americans with Alzheimer’s Disease is projected to reach 13.8 million. 3
Although these statistics can be frightening there is one very important fact we need to keep in mind – Age alone does not cause dementia.
The cause of cognitive decline is complex and multi-faceted. Dementia is typically a slow progressive disease, thought to begin 15-20 years before the symptoms manifest, progressing from mild cognitive impairment to later stage symptoms including confusion, behavioral changes and impaired communication. 1,3
While there is no specific treatment in the management of cognitive decline, research reports that implementing modifiable lifestyle factors may delay or prevent almost 40% of dementia cases. 1
Some Lifestyle and Nutritional Factors Contributing to Alzheimer’s Disease
Stress
Chronic stress causes hypothalamic-pituitary-adrenal (HPA) axis dysfunction which has been associated with cognitive decline and AD. Persistent high cortisol, released from the pituitary gland during stressful events, leads to irreversible damage to the hippocampus impairing memory function. 4
Glucose/Insulin Regulation
Insulin resistance, from a diet high in refined carbohydrates, can impact brain function. Neurons, like other cells in the body, need glucose to function properly. In addition to neuroinflammation associated with high blood sugar, insulin resistance leads to an inability for glucose to enter brain cells resulting in an essential starvation of these cells resulting in impaired cognitive function. Although the brain only comprises about 2% of total body weight it requires about 20% of the body’s total energy.
Additionally, increased adipose tissue associated with insulin resistance leads to systemic inflammation strongly linked AD. 3
Further, insulin acts as a vasodilator; hence with insulin resistance cerebral circulation is diminished.
Advanced Glycation End-products (AGEs)
Although elevated insulin and glucose levels can lead to the formation of AGEs (glycated proteins produced through an interaction with reduced sugars), the primary source of AGEs is dietary. AGEs are found in everyone; however, cooking foods at high temperatures (such as broiling, frying, roasting and grilling) increase these compounds. Elevated levels of serum AGEs have been associated with increased inflammation and risk of AD. 5
Boiling or stewing, boiling or steaming can reduce AGEs by 50%. Further incorporating vinegar or lemon juice to meat can also reduce the formation of AGEs. 5
Homocysteine
Homocysteine is produced from methionine during methylation, an important reaction for many functions in the body, is typically converted back to methionine. However efficient conversion back requires adequate levels of vitamins B12, B6 and folate. Elevated levels of homocysteine (>14 umol/L) almost doubles the risk of dementia.6
Therapeutic Food Plan & Foods
A diet addressing many of the underlying of AD progression, including glucose dysregulation, inflammation and cardiovascular conditions is a great dietary starting point.
MIND diet
Both the Mediterranean diet and DASH diet have demonstrated decreased cognitive decline as well as improvements in the progression of dementia. This combined diet approach, with an emphasis on neuroprotective green leafy vegetables and berries, has been called the MIND diet.
The MIND dietary plan includes vegetables (green leafy >6x/week, others with preference of red-orange >1x/day), legumes, nuts, berries, whole grains, fish, poultry and olive oil while minimizing intake of red meats, cheese, process and fried foods, butter and pastries.
A recent study of the MIND diet reported those following this dietary pattern had a 53% lower risk of developing dementia. 4 Another study investigating this MIND diet demonstrated its neuroprotective effects and slower cognitive decline. The rate of decline from the top tercile of diet adherence to the lowest was equivalent to a 7.5 year age differential. 7
Polyphenols found in many fruits, particularly anthocyanins found in foods such as blueberries and black currants are rich in antioxidants and demonstrated benefit for neuronal health.
In many neurodegenerative diseases, including AD glucose uptake or usage by neurons may be impaired. However, ketones, an alternate source of fuel for the cells, especially brain cells. Medium chain triglyceride oils (MCT) are uniquely transporters for ketones are readily usable forms of cell fuel. 8
Several studies have demonstrated the cognitive benefit of incorporating about 1-2 Tbsp of MCT oil into a daily dietary plan. 9 Further ketone bodies have been suggested to reduce oxidative stress through reactive oxygen species (ROS) regulation. 8
Studies have reported on the effect of serum pesticide levels on cognitive impairment risk and increased risk dementia and AD. DDT pesticide has been reported to significantly increase levels of amyloid-beta in the hippocampus. Similarly, individuals with AD were reported to have a 3.8-fold increased level of serum DDE (a metabolite of DDT). 10 The findings from these studies indicate eating a diet focused on organic foods may reduce the risk of AD.
Therapeutic Food
Numerous studies have demonstrated the health benefits of consuming fatty fish, high in DHA and EPA omega-3 fatty acids. These polyunsaturated long-chain fatty acids have an important role in the structure of cell membranes as well as reducing inflammation and improving synaptic activity (cell-to-cell communication). 4
Several studies have demonstrated the correlation between long-term consumption of about 2 servings of fish each week and lower cognitive decline and decreased level of plasma amyloid-beta linked to reduced risk of AD. 4,5,7
Challenges of Dietary Change Recommendations
Following an organic diet can be challenging due to costs and availability. If financially it’s too far of a stretch, try to focus on foods identified as “Clean 15” by the Environmental Working Group containing low pesticide loads. https://www.ewg.org/foodnews/clean-fifteen.php.
While there is no cure for Alzheimer’s disease, lifestyle modifications can have a strong impact on cognitive function and the prevention or delay of AD. As a progressive disease it’s important to take care of yourself now to best prepare for your future healthy self.
References:
- 2021 Alzheimer’s disease facts and figures. Alzheimers Dement. 2021;17(3):327-406. doi:10.1002/alz.12328
- Hale JM, Schneider DC, Mehta NK, Myrskylä M. Cognitive impairment in the U.S.: Lifetime risk, age at onset, and years impaired [published correction appears in SSM Popul Health. 2020 Dec 10;12:100715]. SSM Popul Health. 2020;11:100577. Published 2020 Mar 31. doi:10.1016/j.ssmph.2020.100577
- Thelen M, Brown-Borg HM. Does Diet Have a Role in the Treatment of Alzheimer’s Disease?. Front Aging Neurosci. 2020;12:617071. Published 2020 Dec 23. doi:10.3389/fnagi.2020.617071
- Kogan M, Soo Jeong H. Chapter 1: Alzheimer Disease. Rakel D. Integrative Medicine. 4th ed. Elsevier, 2018: 95-107.
- Szczechowiak K, Diniz BS, Leszek J. Diet and Alzheimer’s dementia – Nutritional approach to modulate inflammation. Pharmacol Biochem Behav. 2019;184:172743. doi:10.1016/j.pbb.2019.172743
- Seshadri S, Beiser A, Selhub J, et al. Plasma homocysteine as a risk factor for dementia and Alzheimer’s disease. N Engl J Med. 2002;346(7):476-483. doi:10.1056/NEJMoa011613Ross, K. Lecture presented: Module 6 Live Session. Presented as part of Nutrition Intervention Systemic Disorders Week 6, MSCN program at SCNM. Viewed February 8, 2022; Online.
- Ekstrand B, Scheers N, Rasmussen MK, Young JF, Ross AB, Landberg R. Brain foods – the role of diet in brain performance and health. Nutr Rev. 2021;79(6):693-708. doi:10.1093/nutrit/nuaa091
- Jensen NJ, Wodschow HZ, Nilsson M, Rungby J. Effects of Ketone Bodies on Brain Metabolism and Function in Neurodegenerative Diseases. Int J Mol Sci. 2020;21(22):8767. Published 2020 Nov 20. doi:10.3390/ijms21228767
- Fortier M, Castellano CA, Croteau E, et al. A ketogenic drink improves brain energy and some measures of cognition in mild cognitive impairment. Alzheimers Dement. 2019;15(5):625-634. doi:10.1016/j.jalz.2018.12.017
- Yan D, Zhang Y, Liu L, Yan H. Pesticide exposure and risk of Alzheimer’s disease: a systematic review and meta-analysis. Sci Rep. 2016;6:32222. Published 2016 Sep 1. doi:10.1038/srep32222
