CAUSES & RISK FACTORS OF ALZHEIMER’S DISEASE (AD)
Scientists do not yet fully understand what causes Alzheimer’s Disease, but it is clear that it develops because of a complex series of events that take place in the brain over a long period of time. It is likely that the causes include genetic, environmental, and lifestyle factors due to the fact people differ in both their genetics and lifestyle, the importance of these factors in preventing or delaying AD differs from person to person.
Alzheimer’s disease is a progressive disorder characterized by specific brain changes, including the formation and accumulation of abnormal beta-amyloid plaques and neurofibrillary tangles of tau protein. The loss of connection between neurons and increased cell death cause significant brain shrinkage over time. All these changes in tandem cause cognitive impairment, and the person gradually loses their ability to live independently.
What Are The Most Common Alzheimer’s Risk Factors?
Despite being the sixth definitive leading cause of death in the United States, the definite cause of Alzheimer’s disease is still unknown. However, researchers have identified several risk factors that may contribute to its development and further progression.
1. Aging
Although aging does not cause Alzheimer’s disease, it is a significant risk factor. Research shows that the aggregate number of Alzheimer’s patients doubles every five years above age 65. Approximately one-third of all people aged 85 and older may have the disease.
Researchers are focused on determining the connection of age-related brain changes with Alzheimer’s damage. Although age augments the risk, it does not directly cause the disease. For instance, many people may live into their 90s without any signs of dementia.
2. Family History and Genetics
Having a family history of dementia does not imply that an individual will develop the disease. However, it may increase the individual’s risk of getting Alzheimer’s.
Genetics can play a role in some people with Alzheimer’s. A rare type, called early-onset Alzheimer’s disease, affects people aged 30 to 60. Some cases of early-onset AD, called familial AD, are inherited and are caused by risk genes. Familial AD is attributable to mutations (permanent changes) in three genes. Offspring in the same generation have a 50-50 chance of developing familial AD if one parent had it.
The majority of cases are late-onset Alzheimer’s, which develops after age 60. Although a specific gene has not been identified as the cause of late-onset AD, genetic factors do appear to increase a person’s risk of developing the disease. This increased risk is related to the apolipoproteinE (APOE) gene which has several variants. One of them, APOE ε4, occurs in about 40 percent of all people who develop late-onset AD. However, at least one-third of people with AD do not have this form of the gene.
Four to seven other Alzheimer’s risk-factor genes may exist as well. One of those genes, SORL1, was discovered in 2007. Large-scale genetic research studies are currently looking for other risk-factor genes.
3. Lifestyle Risk Factors
Research suggests that certain lifestyle factors, such as a nutritious diet, exercise, social engagement, and mentally stimulating pursuits, might help to reduce the risk of cognitive decline and Alzheimer’s disease. Scientists are investigating associations between cognitive decline and heart disease, high blood pressure, diabetes, and obesity. Understanding these relationships and testing them in clinical trials will help to understand whether reducing risk factors for these diseases is helpful in regards to AD as well.
4. Heart and Vascular Health
Emerging evidence suggests a connection between a healthy brain and a healthy heart because the brain obtains nourishment from one of the richest blood vessel networks, and the heart pumps blood via these vessels to the brain.
Conditions that affect both the heart and vascular health are likely to increase Alzheimer’s risk in an individual. These conditions include heart disease, high blood pressure, stroke, high cholesterol, and diabetes. Avoiding these conditions and maintaining a healthy lifestyle may help keep the heart and brain in good health.
According to the studies performed on the donated brain tissue, plaques and tangles are likely to increase Alzheimer’s onset even further in the presence of stroke or damage to a brain vessel.
5. Head Injury
Research suggests an association between head injury and increased risk of dementia. It is crucial to protect your brain from injuries by wearing helmets when partaking in sports and fall-proofing your home. Traumatic brain injury may impact an individual’s cognitive functions, such as thinking skills, communication and learning.
