Alzheimer's Disease | Causes & Risk Factors


What causes Alzheimer’s disease?

Doctors don’t know exactly what causes Alzheimer’s disease. It appears that Alzheimer’s disease develops when clumps of abnormal proteins grow in the brain. This growth likely begins with a series of many small changes in the brain that start long before any symptoms are noticeable. Over time, these changes add up. Eventually, brain cells become damaged and die.

What are the risk factors for Alzheimer’s disease?

The risk factors for Alzheimer’s disease include the following:

  • Age: The older you are, the greater your risk of developing Alzheimer’s disease. After age 65, your chance of developing Alzheimer’s doubles every 5 years. People who are 85 years of age or older have a nearly 50% chance of having the disease.
  • Genetics and family history: You are more likely to get Alzheimer’s disease if you have a family history of Alzheimer’s disease, meaning that one or more of your parents, siblings, or children has the disease. Scientists also think that certain genes in your DNA may increase your risk for Alzheimer’s disease.
  • Down syndrome: People who have Down syndrome have a much higher risk for Alzheimer’s disease than the general population.
  • Environmental/lifestyle factors: It is likely that your environment and your lifestyle habits also affect your risk for Alzheimer’s disease. A history of head trauma, cardiovascular or heart problems, diabetes, and obesity appear to increase your risk for Alzheimer’s disease. To help prevent these health problems, wear a helmet when riding a bicycle, always buckle your seat belt when in the car, establish a regular exercise routine, eat right, and avoid tobacco products.

Alzheimer’s disease also appears to be more common in women than in men. Nearly two-thirds of people who have Alzheimer’s disease are women.


See a list of resources used in the development of this information.

Written by editorial staff

Reviewed/Updated: 08/12
Created: 04/12