Most modern research suggests Alzheimer’s disease is caused by a combination of age, genetics, family history, and other risk factors (including lifestyle, overall health, brain injury, heart health, etc.).
In this article, we will discuss the many potential causes of Alzheimer’s currently supported by peer-reviewed research.
More than 5.5 million people in the United States live with Alzheimer’s. The vast majority of these are over the age of 65.
Alzheimer’s disease is the most prevalent type of dementia (accounting for 60-80% of cases). What triggers Alzheimer’s disease is amyloid beta, a protein (gunk) that accumulates in the brain and causes the brain’s nerve cells to stop talking to each other.
The inflammation in your brain that seems to lead to this plaque buildup eventually kills the nerve cells in the brain, shrinking the actual size of your brain. Overwhelmingly, this impacts the area where your memories are stored.
A lot of research has centered on identifying a single cause for Alzheimer’s disease. There has also been significant research into the risk factors which increase the likelihood of developing Alzheimer’s disease.
However, the presence of risk factors does not necessarily lead to the development of the amyloid plaques or cognitive decline associated with Alzheimer’s disease.
Many clinical trials show that many pharmaceutical drugs used to treat Alzheimer’s are notably ineffective. However, groundbreaking research into the risk factors, multi-layered causes, and treatment of Alzheimer’s disease shows significant improvement.
Symptoms of Alzheimer’s
These Alzheimer’s symptoms are listed in roughly the order in which they appear:
- Struggle to remember new information
- Organizing and planning difficulty
- A decrease in reasoning skills
- Problems with simple arithmetic
- Loss of balance and depth perception
- Faulty judgment
- Drastic changes in mood
- Shifts in personality
- Severe memory loss
- Proneness to wander
- Inability to respond to the most basic stimuli
In its early stages, Alzheimer’s begins with mild memory loss of recently acquired information.
Recognizing warning signs may allow for early diagnosis and addressing of causative factors in daily life. Subjective Cognitive Decline (SCD) may be most notable to the individual, partner, or caregiver before neurological testing would reveal significant problems.
In this very early stage, the cognitive decline that may lead to Alzheimer’s disease or other dementia can be most dramatically reversed. However, it is always more effective to get ahead of the problem and prevent it entirely than to try reversing it when symptoms appear.
Early signs of Alzheimer’s disease include:
- Difficulty remembering newly acquired information
- Struggles with concentration
- Challenges with common problem solving
- Trouble finding the correct word or entering a conversation
- A decrease in the ability to plan or organize
- Noticeable mood changes
- Mild Cognitive Impairment (MCI)
Who is at risk for Alzheimer’s?
Although the cause of Alzheimer’s disease isn’t fully understood, it is likely a combination of genetic, lifestyle, and environmental components. These components are considered risk factors. Together, they increase the likelihood of developing Alzheimer’s disease.
Research into improving or eliminating as many of these risk factors as possible shows great promise for loved ones, family members, practitioners, and caregivers.
Alzheimer’s affects people from all walks of life, although older age is one significant risk factor. A mutation of the gene that encodes apolipoprotein (APOE) appears to lead to Alzheimer’s disease in older adults, though not the lone factor.
Known causes of Alzheimer’s disease include:
- A buildup of beta-amyloid protein (tau tangles) in the brain
- Chronic inflammation (which may be the underlying root cause of the disease)
- Lifestyle factors
- Environmental toxins
Common risk factors that may lead to Alzheimer’s disease include:
- Advancing age (above 65 years old)
- African-American or Latino ethnicity
- Family history of dementia
- History of concussion
- Heart disease
- High blood pressure
- High cholesterol
- Poor diet
- Lack of exercise
- Tobacco use
- Excessive use of alcohol
- Lack of social activity
- Chronic stress
- Exposure to toxins
More recently, neurodegenerative disease specialist Dr. Dale Bredesen has categorized a list of 36 distinct risk factors for Alzheimer’s disease that he divides into 7 categories. Together, these risk factors have allowed Bredesen to develop a targeted protocol to prevent Alzheimer’s disease.
Aging & Alzheimer’s Disease
Aging is the first of several risk factors that may lead to Alzheimer’s disease. Early-onset Alzheimer’s disease accounts for only about 5% of all cases. Although not everyone who reaches old age will get Alzheimer’s, age is one of the leading risk factors for late-onset Alzheimer’s.
Amyloid plaque builds up between nerve cells in the brain of older adults. Brain cells can no longer adequately communicate. Plaque and tau tangles contribute to mental decline as these nerve cells are killed. These are results from the underlying causes of Alzheimer’s disease, not a direct cause of the disease.
One study has found that each year, there are 4 new cases of Alzheimer’s disease diagnosed per 1,000 adults aged 65-74. That number increases to 32 per 1,000 adults aged 75-84 and 76 per 1,000 adults 85 and over.
After an Alzheimer’s diagnosis, the average life expectancy is 4-8 years.
Long before an Alzheimer’s diagnosis, the brain begins to change — often beginning in your 40s.
However, developing Alzheimer’s or other types of dementia is not a normal part of aging. Advancing age need not inevitably lead to cognitive decline and dementia. The sooner signs of memory problems and possible cognitive decline are detected, the more effective it will be to slow or stop the decline.
Can you stop Alzheimer’s from progressing? In some cases, you may be able to slow down or stop the progression of Alzheimer’s. However, this is difficult and rare. Ultimately, Alzheimer’s is a degenerative disease and a leading cause of death throughout the world.
Genetics & Alzheimer’s Disease
Each person’s genetic map is inherited from their biological parents. Having a family history of Alzheimer’s disease or other types of dementia does not mean you will develop the disease.
However, a family history of Alzheimer’s or another type of dementia is considered a risk factor for possibly developing Alzheimer’s.
There are specific changes or differences in genes that can increase the likelihood of developing Alzheimer’s. Because these are part of our unique genetic makeup inherited from our biological families, the risk for developing Alzheimer’s appears to run in families.
Both early-onset Alzheimer’s and late-onset Alzheimer’s have a genetic component.
There are two categories of genes that influence whether a person will develop a particular disease: risk genes and deterministic genes.
As the name implies, deterministic genes actually cause a disease, while risk genes increase your risk of developing a disease.
Estimates show less than 1% of cases of Alzheimer’s disease are caused by deterministic genes.
Other genetic risk factors include African-American or Latino ethnicity. These may act along with other environmental or lifestyle risk factors increasing the probability of cognitive decline.
The gene that encodes apolipoprotein E (APOE-4) is the best-studied genetic risk factor for Alzheimer’s. It is a mutation of this gene that seems to lead to Alzheimer’s among older adults.
Early-Onset Alzheimer’s vs. Late-Onset Alzheimer’s
Early-onset Alzheimer’s accounts for about 5% of dementia cases and is usually diagnosed between 30 and 60 years of age. Late-onset Alzheimer’s is the most common type of dementia and affects adults over 65 years of age.
Early-onset Alzheimer’s is rare. It is often passed down from parent to child.
3 single-gene mutations are associated with early-onset Alzheimer’s:
- Amyloid precursor protein (APP) on chromosome 21
- Presenilin 1 (PSEN1) on chromosome 14
- Presenilin 2 (PSEN2) on chromosome 1
These gene mutations trigger the production of abnormal proteins associated with Alzheimer’s. There is a 50/50 chance that a child born to a father or mother who carries a genetic mutation for one of these three genes will inherit that mutation. If they inherit the mutation, there is a very high probability that they will develop early-onset Alzheimer’s.
The risk of developing early-onset Alzheimer’s is increased in those with Down Syndrome. It is most likely due to their being born with an extra copy of chromosome 21.
Late-onset Alzheimer’s is the most common type of Alzheimer’s and accounts for 60-80% of dementia cases.
A mutation in the gene that encodes apolipoprotein (APOE-4) may cause Alzheimer’s disease in older adults.
Other Factors That May Contribute to Alzheimer’s Disease
Ongoing research is revealing other causes related to the development of Alzheimer’s disease.
In addition to age-related and genetic factors, other factors that contribute to Alzheimer’s disease include:
- Poor overall health
- Unhealthy lifestyle
- Environmental conditions
- Head injury
- Vascular, neurological, and metabolic health issues
Making changes in your daily life today could reduce the risk of developing many types of dementia decades from now.
For example, higher education levels in some studies have been linked to a decreased risk of developing Alzheimer’s disease. Shared medical appointments for Alzheimer’s prevention have become more common as potential risk factors are identified that can change the course of brain health.
Overall poor health can be a contributing risk factor leading to a beta-amyloid buildup in neurotransmitters associated with Alzheimer’s and other types of dementia.
For example, exercise is vital for life-long health. Many Americans report experiencing some sleep deprivation on a regular basis.
Maintaining good health, supplementing dietary and age-related decreases in essential nutrients and hormones, along with adequate exercise and restful sleep, decrease the risk factors related to developing Alzheimer’s disease.
Healthy physical activity, social engagement, a nutrient-rich healthy diet, good quality sleep, and undertaking mentally stimulating tasks may help reduce the risk of cognitive decline and Alzheimer’s disease as we age.
The buildup of amyloid proteins can be caused by chronic stress and depression. These factors affect younger aging adults and are often difficult to adequately treat.
Environmental factors also affect our probability of developing the brain changes which lead to Alzheimer’s. Toxin exposure is one such environmental factor.
Mold toxicity, environmental chemicals, and air pollution are some of the environmental elements that may lead to cognitive decline.
4. Head Injury
Traumatic head injury, most likely multiple head injuries, contribute to beta-amyloid buildup in the brain. Traumatic brain injury is one of the underlying reasons for this buildup in patients with Alzheimer’s.
Contact sports, auto accidents, and falling are some of the most common causes of traumatic head trauma.
5. Vascular & Neurological Health
Researchers are very interested in the connections between vascular health and the likelihood of developing Alzheimer’s disease.
There appears to be a link between cardiovascular problems such as high blood pressure, heart disease, stroke, and metabolic conditions like obesity and diabetes. Continuing research into this relationship helps us understand possible ways of reducing the risk of Alzheimer’s disease as we age.
Prevention is the Answer.
While no single cause leads to most cases of Alzheimer’s disease, there are many identifiable factors that contribute to developing this condition, such as age, lifestyle, and heart health.
How can Alzheimer’s be prevented? The most effective way to prevent Alzheimer’s disease is to decrease the risk factors associated with it long before you notice symptoms.
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