Older age does not cause Alzheimer’s, but it is the most important known risk factor for the disease.
The number of people with Alzheimer’s disease doubles about every 5 years beyond age 65. About one-third of all people age 85 and older may have Alzheimer’s disease.
Scientists are learning how age-related changes in the brain may harm neurons and affect other types of brain cells to contribute to Alzheimer’s damage.
These age-related changes include atrophy (shrinking) of certain parts of the brain, inflammation, vascular damage, production of unstable molecules called free radicals, and breakdown of energy production within cells.
However, age is only one risk factor for Alzheimer’s disease. Many people live into their 90s and beyond without ever developing dementia.
Research suggests that a host of factors beyond genetics may play a role in the development and course of Alzheimer’s disease.
There is a great deal of interest, for example, in the relationship between cognitive decline and vascular conditions such as heart disease, stroke, and high blood pressure, as well as metabolic conditions such as diabetes and obesity.
Ongoing research will help us understand whether and how reducing risk factors for these conditions may also reduce the risk of Alzheimer’s.
A nutritious diet, physical activity, social engagement, sleep, and mentally stimulating pursuits have all been associated with helping people stay healthy as they age.
These factors might also help reduce the risk of cognitive decline and Alzheimer’s disease. Clinical trials are testing some of these possibilities.
Early-life factors may also play a role. For example, studies have linked higher levels of education with a decreased risk of dementia.
There are also differences in dementia risk among racial groups and sexes—all of which are being studied to better understand the causes of Alzheimer’s disease and to develop effective treatments and preventions for all people.
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