Whether you’re a parent, or a friend of someone with Alzheimer’s disease, you know that there are many different types of causes of this disease.
But what are the most common? You might be surprised to learn that smoking, heart disease, and high cholesterol are some of the most common causes of Alzheimer’s.
The Causes
Despite what you may think, age is not the main cause of Alzheimer’s disease.
Various other factors, including environmental, lifestyle, and genetics play a role in its development.
The symptoms of Alzheimer’s disease include memory problems, personality changes, and trouble carrying out day-to-day activities. It can also affect the ability to think clearly, talk, and make decisions.
The disease is diagnosed by asking questions about a person’s health and past medical conditions. A person with Alzheimer’s develops many more plaques in the brain than someone without the disease.
Some of these plaques are amyloid beta 42, a protein that is produced by the brain and is naturally present. However, the levels of amyloid beta 42 increase with age, which increases the likelihood of clumping together into plaques.
Causes, Factors, and Risks
Having memory loss can be a sign of Alzheimer’s disease, but it isn’t the only one.
Alzheimer’s is a neurological disorder that destroys the brain’s memory and reasoning skills. It’s one of the most common forms of dementia, and it accounts for 60 to 80 percent of all cases of dementia in the U.S.
Researchers do not yet understand why the changes that occur in the brain lead to Alzheimer’s, but it appears that they are caused by plaques and tangles in the brain.
They are formed by beta-amyloid protein, a fragment of a larger protein, which blocks communication between nerve cells.
Alzheimer’s disease is most common in older adults, but it can occur in younger people. Studies have found that people who have a family member with the disease have a greater chance of developing the condition themselves. This type of dementia can be very debilitating, as it destroys the person’s ability to function in daily life.
Family History
Having a family history of Alzheimer’s disease can increase your risk of getting it.
Doctors have known for decades that heredity plays a significant role in the development of dementia. However, scientists do not know what causes the disease or how it can be prevented.
One of these genes, APOE-e4, is the strongest risk gene. About 20-30 percent of the population carries one or two copies of this allele. While not everyone with APOE-e4 develops Alzheimer’s, people with this allele are more likely to get the disease.
One research suggests that a person’s risk of Alzheimer’s is higher if they have a first-degree relative who has the disease. In some families, there is a greater than four-fold increase in the risk of AD if a first-degree relative is affected.
Lifestyle
Studies have shown that the risk of developing Alzheimer’s disease doubles every five years after age 65. It may also be affected by lifestyle choices, such as not smoking. A healthy diet, exercise, and limited alcohol consumption may also reduce the risk.
High Blood Pressure
Until recently, high blood pressure was not considered a significant risk factor for Alzheimer’s disease.
However, recent research shows that controlling it can lower the risk of the disease.
A study from Johns Hopkins University found that individuals who took medication to control their hypertension were less likely to develop Alzheimer’s.
Participants were then allowed to have their brains autopsied to look for brain lesions. They discovered that people with higher blood pressure had more tangles, dead brain tissue, and plaques.
The study was cross-sectional, so it is possible that the results may be subject to ascertainment bias. They found that hypertension was associated with increased circles of Willis atherosclerosis, a common marker of Alzheimer’s disease.
Researchers are unsure of the exact connection between high blood pressure and Alzheimer’s but they think it has to do with the way hypertension promotes the pathology of the disease.
Heart Disease
Several studies have shown that heart disease is a risk factor for Alzheimer’s disease.
Cardiovascular diseases cause damage to the brain, which can lead to cognitive decline and dementia. This includes heart failure, stroke, and heart attack.
Moreover, several studies have found that low diastolic pressure, a type of blood pressure that is below 70 mm Hg, is associated with a greater risk for developing dementia.
One study has shown that people with a high number of vascular risk factors in their midlife are more likely to have higher levels of amyloid in their brain. This is because these vascular health factors could restrict blood flow to the brain, which would increase the buildup of amyloid protein fragments.
Another study found that heart failure and low diastolic blood pressure were independent risk factors for dementia. Moreover, these risk factors were significantly related to poorer cognitive function in the long term.
However, a large-scale study of community-based participants has yet to investigate the relationship between heart failure and Alzheimer’s disease.
Diabetes
Whether diabetes is a cause of Alzheimer’s disease is a question that researchers still cannot answer.
However, it is known that there is a strong link between the two. Several studies have shown that insulin is involved in the development of AD. In the brain, insulin stimulates cerebral glucose metabolism, and insulin insensitivity has been linked to Alzheimer’s disease.
In the brain, insulin binds to IRs located in the hippocampus and cerebral cortex. Insulin stimulates neurotransmitter release and memory processing.
When insulin receptors are disrupted, it results in memory loss. In rats, a single intracerebral injection of insulin improved memory function.
A study found that those with type 2 diabetes had a higher risk of developing AD. The risk was even greater in older patients.
High Cholesterol
Several studies have shown that high cholesterol levels can increase the risk of Alzheimer’s disease.
One study from Emory University has found that high levels of LDL cholesterol may increase the risk of early-onset Alzheimer’s. These results are important because they could help doctors determine the causes of the disease.
In order to determine the association between lipids and dementia, scientists measured the blood of nine hundred and fifty-six thousand five hundred and fifty-three people.
Then they analyzed their genes. They tested for three gene variants: APOB, PSEN1 and PSEN2. These were identified as likely candidates for influencing the risk of Alzheimer’s.
The results showed that people who had high LDL cholesterol at a young age were at increased risk of early-onset Alzheimer’s. But triglyceride levels were only slightly associated with the disease.
Takeaway
The most common causes of Alzheimer’s disease are age, family history and genetic factors. While there is still much research to be done in understanding the exact cause of Alzheimer’s disease, these three factors appear to be the most likely causes.
As such, it is important to be aware of them so that preventive measures can be taken to reduce the risk of developing the disease. Lifestyle changes play the most important role in this fight.
Further research in this area could potentially lead to better treatments or a cure for Alzheimer’s in the future.