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| Alzheimer's Disease: Causes and Risk Factors |
Causes and risk factors
Reasons not fully understood
Scientists
do not yet fully understand the causes of Alzheimer's disease. It
is likely that the causes include a combination of, and lifestyle factors on
the genetic environment. These factors
affect each person differently.
Research shows that Alzheimer's disease causes changes in the brain years or even decades before the first symptoms appear, so that even people who seem free of the disease today may be at risk. Scientists develop sophisticated tests to help identify who is most likely to develop symptoms of Alzheimer's disease. Ultimately, they hope to prevent or delay dementia in these high-risk individuals.
Research shows that Alzheimer's disease causes changes in the brain years or even decades before the first symptoms appear, so that even people who seem free of the disease today may be at risk. Scientists develop sophisticated tests to help identify who is most likely to develop symptoms of Alzheimer's disease. Ultimately, they hope to prevent or delay dementia in these high-risk individuals.
Risk Factors
Some risk factors for Alzheimer's disease, such as age and genetics, can not be controlled. Other factors that may play a role in the development of the disease, such as how a person exercises or socialized-can be changed.
Lifestyle, such as diet and exercise, and health conditions in the long term, such as hypertension and diabetes, may also play a role in the risk of developing Alzheimer's disease. For more information, see the chapter titled "Prevention".
The age-old factor greater risk
Increasing age is the factor most important known risk for Alzheimer's disease. The number of people with the disease doubles every 5 years beyond age 65. Nearly half of those 85 years and older may have Alzheimer's disease. These facts are significant because the number of elderly increases.
Genetics
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There are two types of late onset Alzheimer's disease early.
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There are two types of late onset Alzheimer's disease early.
- Early-onset Alzheimer's disease is a rare form of the disease that occurs in people aged 30 to 60 years. Most of these cases the disease, a hereditary disease caused by mutations or changes in the early onset familial Alzheimer's in some genes.
- Most people with Alzheimer's disease have late onset Alzheimer's disease, which usually develops after age 60. No obvious family pattern is seen in most cases, but genetic factors appear to increase the risk of a person.
Numerous studies have linked the gene for apolipoprotein E in late onset Alzheimer's. One form of this gene, APOE ɛ4 increases the risk of contracting the disease from one person. But many people who get Alzheimer's disease do not have ɛ4 APOE gene and the gene with some people never get Alzheimer's disease.
Scientists have identified a number of other genes, in addition to ApoE ɛ4 that can increase a person's risk for late-onset Alzheimer's disease. Knowing these genes can help researchers to test possible treatments and prevention strategies for people who are at risk of developing Alzheimer's disease more effectively - ideally before symptoms appear.