Causes of Alzheimer’s: Is it Hereditary?
Increasing Cases of Alzheimer’s Disease
The Alzheimer’s Association states that Alzheimer’s disease is the sixth leading cause of death in the U.S. More than five million Americans are affected by this condition. Additionally, one out of three seniors dies of Alzheimer’s or some other type of dementia. That number will likely increase as the aging population increases.
Scientists have been researching Alzheimer’s for decades, but there is still no cure. Learn more in this slideshow about how genes are related to the development of Alzheimer’s, as well as other potential causes of the condition.
What Is Alzheimer’s Disease?
Alzheimer’s disease damages the brain, gradually destroying memory and thinking skills. Researchers believe that the damage begins up to a decade before symptoms appear. Abnormal deposits of proteins form hard plaques and tangles through the brain. These deposits interfere with normal brain function.
As they grow, plaques can interrupt communication between neurons. Neurons are the messengers in the brain. Eventually, these neurons die, and damage becomes so prevalent that certain parts of the brain actually begin to shrink.
Cause #1: Genetic Mutations
So far, Alzheimer’s disease is not fully understood. Scientists believe that for most people, the disease has genetic, lifestyle, and environmental factors. All these factors may work together to create the right conditions for the disease to take root.
There is a hereditary component to Alzheimer’s. People whose parents or siblings have the disease are at a slightly higher risk of developing the condition. The Mayo Clinic notes, however, that we’re still a long way from understanding the genetic mutations that lead to the actual development of the disease.
Cause #2: Age
As we get older, we become more vulnerable to the factors that can cause Alzheimer’s. In 2010, there were 4.7 million individuals aged 65 years and older with Alzheimer’s disease. Of these, 0.7 million were 65 to 74 years old, 2.3 million were between 75 and 84 years old, and 1.8 million were 85 years or older.
Cause #3: Gender
Alzheimer’s affects more women than men. Scientists theorize this is because women live longer than men, in general, and thus are more likely to contract the disease in their late senior years.
A 2010 study also suggested that hormones might have something to do with it. The level of the female hormone estrogen decreases in the body after menopause. Researchers believe that the hormone protects the brains of young women from damage, but as levels plunge in older age, brain cells become more vulnerable.
Cause #4: Past Head Trauma
The Alzheimer’s Association notes that scientists have found a link between traumatic brain injury and greater risk of dementia. The University of Washington Alzheimer’s Disease Research Center agrees. They state that immediately after a traumatic injury, the brain creates large amounts of beta amyloid. This is the same protein that develops into the damaging plaques that are a hallmark trait of Alzheimer’s.
There is one difference: after a traumatic brain injury, beta amyloid, although present, does not clump into plaques. However, the damage may increase the risk of them doing so later on in life.
Cause #5: Mild Cognitive Impairment
People who already have mild cognitive impairment may be at an increased risk of developing full-blown Alzheimer’s. A mild cognitive impairment doesn’t necessarily impact a person’s daily life in a major way. It may, however, have some effects on memory, thinking skills, visual perception, and the ability to make sound decisions.
Scientists are trying to understand why some cases of mild cognitive impairment progress to Alzheimer’s, and others don’t. A 2006 study, for example, noted that the presence of certain proteins in the brain, like beta amyloid, increased risk of the disease.
Cause #6: Lifestyle and Heart Health
Our lifestyle may have a lot to do with our likelihood of developing Alzheimer’s. Heart health, in particular, seems to be closely related to brain health. Eating a healthy diet, exercising regularly, quitting smoking, controlling diabetes, and controlling blood pressure and cholesterol, which are all good for the heart, can also keep the brain healthy and resilient.
A 2005 study, for instance, noted that older adults with coronary artery disease or peripheral arterial disease had a higher risk of dementia and Alzheimer’s disease.
Cause #7: Sleep Disorders
Some research has indicated that quality sleep may be important for prevention of Alzheimer’s disease. A 2013 study published in JAMA Neurology surveyed adults with an average age of 76 who had not been diagnosed with the disease. Those who experienced poor or limited sleep had an increased buildup of beta amyloid plaques in the brain.
More studies need to be done. Scientists still aren’t sure whether poor sleep is a cause of Alzheimer’s, or if the early stages of the disease may affect sleep. Both may be true.
Cause #8: Lack of Lifetime Learning
How much we use our brains over the course of our lives may also affect our risk of Alzheimer’s. A 2012 study reported that people who regularly stimulated their brains with challenging mental activities had fewer beta amyloid deposits. These activities were important all through life, but early and middle life efforts were associated with the biggest reduction in risk.
The Mayo Clinic adds that higher levels of formal education, a stimulating job, mentally challenging leisure activities, and frequent social interactions may also protect brain health.
- About Alzheimer's Disease: Alzheimer's Basics. (n.d.). National Institute on Aging. Retrieved November 8, 2013, from http://www.nia.nih.gov/alzheimers/topics/alzheimers-basics
- Alzheimer’s disease: Causes. (2013, January 8). Mayo Clinic. Retrieved November 8, 2013, from http://www.mayoclinic.com/health/alzheimers-disease/DS00161/DSECTION=causes
- Alzheimer’s disease: Risk factors. (2013, January 19). Mayo Clinic. Retrieved November 26, 2013, from http://www.mayoclinic.com/health/alzheimers-disease/DS00161/DSECTION=risk-factors
- Hansson, O. et al. (2006). Association between CSF biomarkers and incipient Alzheimer's disease in patients with mild cognitive impairment: a follow-up study. Lancet Neurology, 5(4), 228-234. Retrieved November 8, 2013, from http://www.ncbi.nlm.nih.gov/pubmed/16488378
- Hebert, L.E. et al. (2013, February 6). Alzheimer disease in the United States (2010-2050) estimated using the 2010 census. Neurology. Retrieved November 8, 2013, from http://www.neurology.org/content/early/2013/02/06/WNL.0b013e31828726f5.abstract
- Landau, S.M. (2012). Association of Lifetime Cognitive Engagement and Low β-Amyloid Deposition. JAMA Neurology, 69(5), 623-639. Retrieved November 8, 2013, from http://archneur.jamanetwork.com/article.aspx?articleid=1149704
- Latest Facts & Figures Report. (2013). Alzheimer's Association. Retrieved November 8, 2013, from http://www.alz.org/alzheimers_disease_facts_and_figures.asp
- Newman, A.B. et al. (2005, July). Dementia and Alzheimer's disease incidence in relationship to cardiovascular disease in the Cardiovascular Health Study cohort. Journal of the American Geriatric Society, 53(7), 1101-1107. Retrieved November 8, 2013, from http://www.ncbi.nlm.nih.gov/pubmed/16108925
- Spira, A.P. et al. (2013, October 21). Self-reported Sleep and β-Amyloid Deposition in Community-Dwelling Older Adults. JAMA Neurology. Retrieved November 8, 2013, from http://archneur.jamanetwork.com/article.aspx?articleid=1757019
- Traumatic Brain Injury. (n.d.). Alzheimer's Disease and Dementia. Retrieved November 8, 2013, from http://www.alz.org/dementia/traumatic-brain-injury-head-trauma-symptoms.asp#dementiaandinjury
- Traumatic Brain Injury and Alzheimer's Disease. (2013). University of Washington Alzheimer’s Disease Research Center. Retrieved November 8, 2013, from http://depts.washington.edu/adrcweb/research-101/traumatic-brain-injury/
- Viña J. & Lloret, A. (2010). Why women have more Alzheimer’s disease than men: gender and mitochondrial toxicity of amyloid-beta peptide. J Alzheimers Dis., 20(Suppl. 2), S527-S533. Retrieved November 8, 2013, from http://www.ncbi.nlm.nih.gov/pubmed/20442496
- What is Alzheimer's Disease. (n.d.). NIHSeniorHealth. Retrieved November 8, 2013, from http://nihseniorhealth.gov/alzheimersdisease/whatisalzheimersdisease/01.html