As I have noted elsewhere (see HERE), the cause (or causes) of Alzheimer’s Disease is unknown at present. However, according to researchers, there are certain conditions, properties, or states of affairs that seem to raise the probability that a given individual will develop Alzheimer’s. These qualities, collectively and singly, are known as risk factors.
The biggest risk factors for getting Alzheimer’s are age (your chances increase as you get older) and genetics (especially if you’re a carrier of the ApoE4 gene). But there are others as well, for example having other diseases (like diabetes and Down’s Syndrome), conditions (such as atherosclerosis, high blood pressure, high cholesterol, and traumatic brain injury), or habits (chiefly, smoking) that predispose you toward dementia.
Preliminaries
Basics
Alzheimer’s is a neurodegenerative disease in which a person experiences drastic losses in cognitive abilities and memory. Patients suffering from it develop a bunch of “junk” in their brains – protein deposits of various sorts that conglomerate into abnormal structures referred to as “plaques and tangles” – that disrupts neural signals and kills off brain cells. These structures accumulate excessively and are not considered to be a part of the “normal” aging process.
“As in [normal] aging, widespread neuron loss and decreases in synaptic density are observed, though Alzheimer’s disease results in a significant preferential effect in the neocortex, hippocampus, amygdala, and basal nucleus of Meynert… Normal aging can result in the formation of plaques and tangles, but the amount and distribution does not compare to the brains of people with Alzheimer’s disease, in which greater quantities are common, especially in regions such as the temporal lobe.”[1]
- For more information on the general contours of the ailment, see my “What Is Alzheimer’s Disease? A Brief Overview.”
History
“The disease was first discovered in 1906 and described in a clinical journal article in 1907 by Alois Alzheimer, M.D. a German neurologist. He had first recognized the peculiar symptoms in one of his patients. a fifty-five-year-old woman. Dr. Alzheimer then referred to this disease in a published article as presenile dementia.
“Neurologists now agree that the dementia that occurs in the elderly is the same as or similar to the presenile condition. It is usually referred to today as senile dementia of the Alzheimer’s type (SDAT — more commonly leaving off the word ‘senile,’ medical specialists designate it just as DAT or Alzheimer’s disease).”[2]
- I have gone into much greater depth on the history of Alzheimer’s Disease elsewhere. For an introduction, see: “How Long Has Alzheimer’s Dementia Been Around?”
Cause(s)
Scientists have not yet determined a definite – let alone single – cause for Alzheimer’s Disease. Rather, there are a variety of postulated causes. These include the development of the previously mentioned plaques and tangles, sharp decreases in sex hormones (such as estrogen and testosterone) or neurotransmitters (like acetylcholine), chronic exposure to or excessive accumulation of toxins (e.g., aluminum or mercury), and so on.
- To read more in this vein, see: “10 Possible Causes for Alzheimer’s (& How to Address Them)”; “Can Drinking Alcohol Causes Alzheimer’s Disease?”; and “Can Contaminated/Dirty Tap Water Cause Alzheimer’s Disease?”
Risk Factors[3]
“Although an exact cause has not been identified, scientists have found several risk factors associated with Alzheimer’s disease. A risk factor predisposes someone to developing the disease. This means that someone with a risk factor is more likely to get a disease than someone without it.”[4]
“Risk factors for cognitive decline in aging are multifactorial, including medical co-morbidities and familial genetic risk.”[5]
Age
It turns out that, for everyone, the risk of developing Alzheimer’s goes up as we advance in years. This is repeated by numerous sources across the spectrum, from mainstream medical and scientific sources to more offbeat alternatives.
So, we read: “Age is the most important known risk factor for A[lzheimer’s] D[isease]. The number of people with the disease doubles every 5 years beyond age 65.”[6] And, again, alternative health guru Dr. Joseph Mercola states: “Your single greatest risk factor for Alzheimer’s disease is your age.”[7]
This is true as far as it goes. But there are other important factors. One is genetic.
Genes
“The gene apolipoprotein E-e4 (APOE-e4) has been identified as a …factor that most likely increases [the risk of] developing Alzheimer’s.”[8]
“Alzheimer’s disease is a neurodegenerative disorder mostly seen in the elderly. Presence of at least one apolipoprotein E4 (ApoE) allele is the strongest yet known genetic risk factor of late-onset Alzheimer’s disease. …Mutations of the genes encoding the [beta]-amyloid precursor protein and the presenilins 1 and 2 are risk factors for the early-onset form of Alzheimer’s disease. …”[9]
Family History
“Having a family history of dementia …[is] a risk factor for Alzheimer’s disease.”[10] Numerous studies have confirmed this.[11]
Contrariwise: “Subjects with A[lzheimer’s] D[isease] had a higher risk of having a family history of AD …as compared to control subjects.”[12]
Obesity
When a person is drastically more massive than is healthy for his or her height, the person might be said to be “obese.” “[A]ccumulating evidence links obesity to increased risk of Alzheimer’s and other types of dementia later in life…”.[13]
What is alarming – albeit somewhat intriguing – is that “[o]besity …[is] recognized as an important player in the pathogenesis of …dementia …independently of insulin resistance or other vascular risk factors.”[14] In other words, obesity isn’t just a factor because of increased risk of diabetes or hypertension or other factors listed elsewhere.
Sex
Is it possible that being female is actually an Alzheimer’s risk factor?
Indeed, one author reports: “It [has been] suggested …that female gender could act as a risk factor for Alzheimer’s disease…”.
However, researchers are unsure whether this is, in fact, a separate factor. The aforementioned writer goes on to state: “but it appears …that women are at higher risk because of their relatively increased longevity.”[15]
If this is the case, then really sex is itself not a distinct risk factor. It’s just that women are likely to outlive men. Since, as we’ve already said, the older a person gets, the greater his or her risk for Alzheimer’s, it follows that if women live longer than men, then they’ll be more likely than their male counterparts to get dementia.
Other Diseases
Furthermore, there are links between various other conditions and Alzheimer’s. “Some evidence points to risk factors similar to those for heart disease, including no physical exercised, high blood pressure and high cholesterol, a diet low in fruits and vegetables, and smoking.”[16]
Hardening of the Arteries (Atherosclerosis)
For example, there is a connection between “Alzheimer[‘s] neuropathology” and “atherosclerosis.” Atherosclerosis is termed a “vascular” disease because it afflicts the blood vessels of susceptible people. It’s sometimes referred to as a “hardening” of the arteries due to the fact that atherosclerosis involves gunk building up on the inside of those anatomical tubes.
These deposits are usually made of fat and, like their neurological cousins, are called plaques. One might get the impression that atherosclerosis and Alzheimer’s might both be characterized by the bioaccumulation of garbage inside the body.
From my point of view, this underscores the importance of living an overall healthy lifestyle, including getting adequate exercise and sleep as well as maintaining a proper diet. For more on some of these, see: “The Alzheimer’s ‘MIND Diet’: What Should You Eat?”; “Alzheimer’s and Sleep: Too Little, Too Much, and Just Right”; and “Alzheimer’s and Sleep: Herbs, Spices, and Other Supplements.”
However, it is worth noting that “atherosclerosis …[is] potentially reversible” and the link between it and dementia is far from being completely understood.[17]
Diabetes
In general, diabetes is a malfunction in a person’s ability to handle insulin, an essential, glucose-regulating hormone produced in the pancreas. This malfunction results in out-of-whack blood-sugar levels. There are two sorts of diabetes: Type 1 and Type 2. A person with the former must receive insulin from an external source, as his or her body produces little or none of it. Type 2 is generally regarded as less severe than Type 1, since a sufferer’s body is usually able to produce some insulin. Therefore, a Type-2 diabetic is not “insulin-dependent” in the same way as is a Type-1 diabetic.
“People with diabetes mellitus are at increased risk of cognitive dysfunction and dementia.”[18]
Down’s Syndrome
Down’s Syndrome is a genetic disorder. This condition arises when there is an extraneous copy of one chromosome (#21) in a parent’s (haploid) reproductive cells (gametes). This results in a sperm or egg cell with 24 chromosomes, instead of the usual 23. Combined with a normal gamete, the resulting offspring has 47 total chromosomes.
“People with Down’s syndrome …are at high risk for developing Alzheimer’s disease …at a relatively young age.”[19]
High Cholesterol (Hyperlipidemia; Hypercholesterolemia)
Cholesterol is a type of fat (or lipid) that is circulated in the body via the blood. It is produced by the liver and obtained in various foods (e.g., eggs). The body uses cholesterol to build new cells. So, having some of it is a good and necessary thing.
However, medical science is generally worried about the amount of cholesterol in your body. If it’s too high, the thinking goes, it can literally gummy up your blood vessels and increase your risk for cardiovascular and heart diseases.
Interestingly, “[s]everal lines of evidence have linked cholesterol to dementia.”[20]
Part of the reason for this may be because when blood flow is impeded, available oxygen can decrease. The brain is highly sensitive to oxygen deprivation. Hence, if the brain is not properly oxygenated, the deficit can cause damage that can lead to dementia.
High Blood Pressure (Hypertension)
Other “risk factors …[include] hypertension.” Because of this, and besides increasing “cognitive engagement,” researchers suggest that getting “regular physical activity …[, eating] the Mediterranean diet and …[consuming] omega-3 fatty acids …may reduce the risk of Alzheimer’s disease…”.[21]
Physical Brain Injury
There are also various external risk factors. “Head trauma …[is] is risk factor for Alzheimer’s disease…”.[22]
“Moderate-to-severe traumatic brain injury is one of the strongest environmental risk factors for the development of neurodegenerative diseases such as late-onset Alzheimer’s disease, although it is unclear whether mild traumatic brain injury, or concussion, also confers risk.”[23]
This is a difficult factor to track precisely “[s]ince people with Alzheimer’s disease …[are] bound to have poor recollection of the exposure to head trauma…”.[24]
Aluminum
In discussions of environmental risk factors, the light metal Aluminum (Al) has been brought up repeatedly. It has been associated both with the development both of the beta-amyloid plaques and the tau-protein neurofibrillary tangles that are characteristic of Alzheimer’s-riddled brains.
One writer states “that even miniscule amounts of aluminum can boost the production of beta-amyloid” and that “aluminum seems to misfold tau [proteins], which would boost the risk of the typical tangles of Alzheimer’s.”[25]
“There has been suggestion of interaction between aluminum and several A[lzheimer’s] D[isease]-associated pathways.”[26]
This warning turns up in some rather unexpected places. Writing in his popular introduction on the ancient proto-science of Alchemy, Dennis Hauck writes as follows.
“Don’t use aluminum pots and pans or utensils when making alchemical products. Modern alchemists feel that aluminum metal acts as a kind of ‘energy sponge; that depletes spiritual energy. Several scientific studies seem to support the alchemists’ suspicions and have linked aluminum to mental retardation and Alzheimer’s disease.”[27]
- For more on heavy-metal and other kinds of environmental toxicity, see “Toxic Alzheimer’s? Household Hazards: Gases, Molds, Poisons” and “Household Hazards for People With Dementia.”
Smoking
Smoking is so strongly correlated with lung disease that the habit is believed to cause numerous health problems including chronic bronchitis, chronic obstructive pulmonary disease (COPD), emphysema, and even lung cancer.
Moreover, according to author Frank Murray, “smoking is definitely a significant risk factor for Alzheimer’s disease…”.[28]
Combined Risk Factors
Unsurprisingly, if factors are combined, then a person’s expected risk goes up. I won’t list all the various combinations, and I’m not a statistician. But, here are a couple of examples.
“Elderly people with type-2 diabetes have an 8.8 percent increase[d] risk of developing dementia, including Alzheimer’s disease.”[29]
Or, again: “Family history of Alzheimer’s disease and APOE-4 status [together] were associated with” several, physical brain abnormalities, including “a thinner cortex in the entorhinal region, subiculum, and adjacent medial temporal lobe subfields.”[30]
For Further Reading
- “Protect Yourself Against the coming Dementia Crisis”
- “10 Things to Do NOW to Reduce Your Risk of Alzheimer’s Later”
- “Top 25 Herbs for Treating (& Avoiding) Alzheimer’s Dementia”
Notes:
[1] Ronald Watson and Fabien De Meester, eds., Omega-3 Fatty Acids in Brain and Neurological Health, Amsterdam: Academic Press; Elsevier, 2014, p. 209, <https://books.google.com/books?id=HFgXAwAAQBAJ&pg=PA209>.
[2] Herman Richard Casdorph and Morton Walker, Toxic Metal Syndrome, New York: Avery; Penguin, 1995, p. 18, <https://books.google.com/books?id=7GJEveEcurMC&pg=PA18>.
[3] For more information, see Dementia: New Insights for the Healthcare Professional, 2011 ed., Atlanta: ScholarlyEditions, 2012, passim., <https://books.google.com/books?id=u89Efydxk7MC>.
[4] Linda Lu and Juergen Bludau, Alzheimer’s Disease, Santa Barbara, Cal.: ABC-CLIO, 2011, p. 16, <https://books.google.com/books?id=6gskihyGEQ0C&pg=PA16>.
[5] Lisa Morrow, Beth Snitz, Eric Rodriquez, Kimberly Huber, and Judith Saxton, “High Medical Co-Morbidity and Family History of Dementia is Associated With Lower Cognitive Function in Older Patients,” Family Practice, vol. 26, no. 5, Oct. 2009, pp. 339-343, <https://academic.oup.com/fampra/article/26/5/339/636444>.
[6] Eileen Welsh, ed., Frontiers in Alzheimer’s Disease Research, New York: Nova Science Publ., 2006, publisher’s blurb, <https://books.google.com/books/about/Frontiers_in_Alzheimer_s_Disease_Researc.html?id=dpMdC21dU9YC>.
[7] Joseph Mercola, Dark Deception: Discover the Truths About the Benefits of Sunlight Exposure, Nashville, Tenn.: Thomas Nelson, 2008, p. 71, <https://books.google.com/books?id=ay99sWUvTxoC&pg=PA71>.
[8] Jean Kaplan Teichroew, “Alzheimer’s,” Jean Kaplan Teichroew, ed., Chronic Diseases: An Encyclopedia of Causes, Effects, and Treatments, Santa Barbara, Cal.: ABC-CLIO, 2016, p. 53, <https://books.google.com/books?id=Am91DQAAQBAJ&pg=PA53>.
[9] Marcus Portallis, Focus on Hormone Replacement Research, New York: Nova Biomedical Publ., 2004, p. 87, <https://books.google.com/books?id=xWXSNNasBcEC&pg=PA87>.
[10] Ezra Susser, Sharon Schwartz, Alfredo Morabia, and Evelyn Bromet, with Melissa Begg, Jack Gorman, and Mary-Claire King, Psychiatric Epidemiology: Searching for the Causes of Mental Disorders, New York: Oxford Univ. Press, 2006, p. 367, <https://books.google.com/books?id=y6AN6bpfJhgC&pg=PA196>.
[11] See, e.g., D. Forster, A. Newens, D. Kay, and J. Edwardson, “Risk Factors in Clinically Diagnosed Presenile Dementia of the Alzheimer Type: A Case-Control Study in Northern England,” Journal of Epidemiology and Community Health, vol. 49, no. 3, Jun. 1995, pp. 253-258, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1060793/> and M. Rajah, L. Wallace, E. Ankudowich, E. Yu, A. Swierkot, R. Patel, M. Chakravarty, D. Naumova, J. Pruessner, R. Joober, S. Gauthier, and S. Pasvanis, “Family History and APOE4 Risk for Alzheimer’s Disease Impact the Neural Correlates of Episodic Memory by Early Midlife,” NeuroImage: Clinical, vol. 14, Mar. 31, 2017, pp. 760-774, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5385589/ >.
[12] Ami Rosen, N. Kyle Steenland, John Hanfelt, Stewart Factor, James Lah, and Allan Levey, “Evidence of Shared Risk for Alzheimer’s Disease and Parkinson’s Disease Using Family History,” Neurogenetics, vol. 8, no. 4, Sept. 6, 2007, pp. 263-270, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2679377/>.
[13] Scott Kanoski, Ted Hsu, and Steven Pennell, “Obesity, Western Diet Intake, and Cognitive Impairment,” Ronald Ross Watson, Omega-3 Fatty Acids in Brain and Neurological Health, Amsterdam: Elsevier; Academic Press, 2014, p. 57, <https://books.google.com/books?id=HFgXAwAAQBAJ&pg=PA57>.
[14] L. Letra, I. Santana, R. Seiça, “Obesity as a Risk Factor for Alzheimer’s Disease: The Role of Adipocytokines,” Metabolic Brain Disease, vol. 29, no. 3, Feb. 20, 2014, pp. 563-568, <https://www.ncbi.nlm.nih.gov/pubmed/24553879>.
[15] Portallis, Focus on Hormone Replacement Research, loc. cit.
[16] Teichroew, “Alzheimer’s,” Teichroew, ed., Chronic Diseases, loc. cit.
[17] See H. Dolan, B. Crain, J. Troncoso, S. Resnick, A. Zonderman, and R. Obrien, “Atherosclerosis, Dementia, and Alzheimer [sic] Disease in the Baltimore Longitudinal Study of Aging Cohort,” Annals of Neurology, vol. 68, no. 2, Aug. 2010, pp. 231-240, <https://www.ncbi.nlm.nih.gov/pubmed/20695015>.
[18] Yael Reijmer, Esther van den Berg, Carla Ruis, L. Kappelle, and Geert Biessels, “Cognitive Dysfunction in Patients With Type 2 Diabetes,” Diabetes, vol. 26, no. 7, Aug. 26, 2010, pp. 507-519, <https://onlinelibrary.wiley.com/doi/10.1002/dmrr.1112>.
[19] Paula Castro, Shahid Zaman, and Anthony Holland, “Alzheimer’s Disease in People With Down’s Syndrome: The Prospects for and the Challenges of Developing Preventative Treatments,” Journal of Neurology, vol. 264, no. 4, Oct. 24, 2016, pp. 804–813, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5374178/>.
[20] A. Solomon, R. Sippola, H. Soininen, B. Wolozin, J. Tuomilehto, T. Laatikainen, and M. Kivipelto, “Lipid-Lowering Treatment Is Related to Decreased Risk of Dementia: A Population-Based Study,” Neuro-Degenerative Diseases, vol. 7, nos. 1-3, Apr. 2010, pp. 180-182, <https://www.karger.com/Article/Abstract/295659>.
[21] Yoram Barak, Preventing Alzheimer’s Disease: Personal Responsibility, New York : Nova Biomedical, 2014, publisher’s blurb, <https://books.google.com/books/about/Preventing_Alzheimer_s_Disease.html?id=tqiQvgEACAAJ>. Note that hypertension is also a risk factor for the second most common form of dementia, Vascular. See Sarah Jacobsen, Vascular Dementia: Risk Factors, Diagnosis, and Treatment, New York: Nova Science, 2011.
[22] Susser, Schwartz, Morabia, and Bromet, et al., Psychiatric Epidemiology, op. cit., p. 196.
[23] J. Hayes, M. Logue, N. Sadeh, J. Spielberg, M. Verfaellie, S. Hayes, A. Reagan, D. Salat, E. Wolf, R. McGlinchey, W. Milberg, A. Stone, S. Schichman, and M. Miller, “Mild Traumatic Brain Injury Is Associated With Reduced Cortical Thickness in Those at Risk for Alzheimer’s Disease,” Brain, Mar. 1, 2017, vol. 140, no. 3, pp. 813-825, <https://www.ncbi.nlm.nih.gov/pubmed/28077398>. In fact, the condition known as Dementia Pugilistica, previously referred to as “punch-drunk syndrome,” afflicts people — e.g., boxers and athletes involved in “contact” sports such as football/gridiron, hockey, martial arts, rugby, and wrestling — who experience damage to or disease of the brain due to repeated injury (such as blows to the head).
[24] Susser, Schwartz, Morabia, and Bromet, et al., Psychiatric Epidemiology, op. cit., p. 201.
[25] Jeffrey Victoroff, Saving Your Brain: The Revolutionary Plan to Boost Brain Power, Improve Memory, and Protect Yourself Against Aging and Alzheimer’s, New York: Bantam Books, 2003, p. 168, <https://books.google.com/books?id=M5SqLEYbWPAC>.
[26] A. Castorina, A. Tiralongo, S. Giunta, M. Carnazza, G. Scapagnini, and V. D’Agata, “Early Effects of Aluminum Chloride on Beta-Secretase mRNA Expression in a Neuronal Model of Beta-Amyloid Toxicity,” Cell Biology and Toxicology, vol. 26, no. 4, Jan. 29, 2010, pp. 367-377, <https://www.ncbi.nlm.nih.gov/pubmed/20111991>.
[27] Dennis Hauck, The Complete Idiot’s Guide to Alchemy, New York: Alpha; Penguin, 2008, p. 186, <https://books.google.com/books?id=SsolrTciALUC&pg=PA186>.
[28] Frank Murray, Minimizing the Risk of Alzheimer’s Disease, New York: Algora Publishing, 2012, p. 264, <https://books.google.com/books?id=9hveCHdjkt4C&pg=PA264>.
[29] Murray, Minimizing the Risk of Alzheimer’s Disease, op. cit., p. 255, <https://books.google.com/books?id=4f8Nj83E3R8C&pg=PA255>.
[30] Markus Donix, Alison Burggren, Nanthia Suthana, Prabha Siddarth, Arne Ekstrom, Allison Krupa, Michael Jones, Laurel Martin-Harris, Linda Ercoli, Karen Miller, Gary Small, and Susan Bookheimer, “Family History of Alzheimer’s Disease and Hippocampal Structure in Healthy People,” The American Journal of Psychiatry, vol. 167, no. 11, Aug. 4, 2010, pp. 1399-1406, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3086166/>.