Alzheimer's Disease Causes

A risk factor is something that increases your likelihood of getting a disease or condition.

It is possible to develop Alzheimer’s disease with or without the risk factors listed below. However, the more risk factors you have, the greater your likelihood of developing Alzheimer’s disease.

There are still many questions regarding the exact cause of Alzheimer’s disease, so risk factors are still being identified. Currently, risk factors for Alzheimer’s disease include:

Age

Age is the most important known risk factor for developing Alzheimer’s disease. The number of people with Alzheimer’s disease doubles every five years beyond age 65 until age 85, when almost 50% of all people have the disease.

Gender

Alzheimer’s disease affects both men and women, but women may have a slightly higher risk of developing the disease than men. Some experts believe that this is due to the fact that women live longer than men, but others dispute this claim.

Genetic Factors

Individuals with a first-degree relative of someone with Alzheimer’s disease (a parent or sibling) have a two- to three-times risk of developing the disease when compared to the rest of the population. In addition, there has been a clear genetic link established for an early-onset form of Alzheimer’s disease (occurs in people during their 30s, 40s, and early 50s), and a genetic link is suspected for late-onset Alzheimer’s disease. However, a specific gene has not yet been identified. One gene that has been implicated as being a major risk factor for late-onset Alzheimer’s disease is the ApoE4 gene. Scientists continue to study the role of genetic factors in the development of this disease.

Medical Conditions

• Head injury —There are some studies that suggest that people who suffered a serious, traumatic head injury at some time in their lives may be at higher risk of developing Alzheimer’s disease.

• Down syndrome —Nearly all people with Down syndrome who live to be age 40 or older develop Alzheimer’s disease.

• High cholesterol and high blood pressure

• Vitamin B12 deficiency —Low levels of the vitamin B12 and folate have been linked to a development of Alzheimer’s disease.

• Depression and anxiety

• Overweight or obese

• Diabetes

Mental Activity and Education

Some research has suggested that people who have higher education levels and continue to be mentally active and engaged in their later years are less likely to develop Alzheimer’s disease. However, some experts suggest that this finding may actually be due to the fact that those with higher education levels tend to do better on the psychological tests used to diagnose Alzheimer’s.

Environment

Some theories suggest that Alzheimer’s disease may be linked to exposure to certain environmental factors, such as toxins, certain viruses and bacteria, certain metals, or electromagnetic fields. Currently, there is no conclusive evidence to support these theories.

References:

Alzheimer's disease. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated March 2009. Accessed April 1, 2009.

Dementia. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated November 2009. Accessed November 6, 2009.

Risk factor. Alzheimer’s Association website. Available at: http://www.alz.org/ . Accessed April 1, 2009.

8/23/2010 DynaMed's Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Ritchie K, Carrière I, Ritchie CW, Berr C, Artero S, Ancelin ML. Designing prevention programmes to reduce incidence of dementia: prospective cohort study of modifiable risk factors. BMJ.2010;341:c3885.