Risk Factors for Alzheimer’s Disease

Reviewed by: HU Medical Review Board | Last reviewed: January 2023

There is no single reason people develop Alzheimer’s disease. For each person who has it, there are a variety of factors at play. But doctors are aware of some risk factors for Alzheimer’s. These risk factors increase the odds of anyone developing Alzheimer’s.1-3

These factors do not directly cause Alzheimer’s disease. They may each contribute in small ways to how the disease develops and progresses. Some risk factors are out of people’s control, like family history or age. But there are some risk factors that you are able to control throughout your life.1-3

Age

Some people think that Alzheimer’s is only caused by aging. Though aging increases risk, it is not a direct cause.1

Most people with Alzheimer’s disease are 65 or older. After someone turns 65, their risk of Alzheimer’s doubles every 5 years. Once they turn 85, the risk of Alzheimer’s is nearly one-third. Alzheimer’s also accounts for nearly two-thirds of dementia for people who are 65 and older.1,2

It is possible to develop Alzheimer’s before age 65. This is called early-onset. It is seen in about 5 percent of people with Alzheimer’s. Early-onset Alzheimer’s is primarily inherited (passed down in families) through the genes.2

Genetics and family history

Alzheimer’s can be inherited as an autosomal dominant disorder. This means that even if only one parent has the gene for Alzheimer’s and passes it to their child, the child will likely develop Alzheimer's as well. A family history of inherited Alzheimer’s, especially in the immediate family, indicates a high risk that a person will get the disease (but not always).1

The majority of genetic Alzheimer’s is early-onset. There are 3 primary genes responsible in these cases:2

  • Presenilin 2, which is found on chromosome 1
  • Presenilin 1 on chromosome 14
  • The AAP gene on chromosome 21

Many times, these genes can be analyzed using genetic testing.2

Other health factors

Other aspects of your health can increase the risk of having Alzheimer’s disease. Even though these factors do not directly cause Alzheimer’s, they can still make an impact.1,3

Heart health is a main risk factor because damage to the blood vessels can keep harmful substances from being cleared away from different parts of the brain. The beta-amyloid plaques and neurofibrillary tangles that cause Alzheimer’s are more harmful if someone has damage in the blood vessels of their brain. Heart and blood vessel damage may be caused by:1,3

  • Heart disease
  • Diabetes
  • Stroke
  • High blood pressure
  • High cholesterol

Type 2 diabetes also affects Alzheimer’s risk. People with type 2 diabetes are nearly twice as likely to develop Alzheimer’s as people without type 2 diabetes. Some studies show this risk may be reduced through better diabetes management and lifestyle changes such as not smoking.3

Lastly, people with a history of traumatic brain injury have a higher risk of all dementias, including Alzheimer’s. This is particularly important for men, who have a higher risk of dementia due to traumatic brain injury than women.3

Lifestyle factors

There are also many lifestyle choices that can be risk factors for Alzheimer’s. These can be health related – like heart attack, stroke, high blood pressure, diabetes, and obesity. Smoking has been linked to both positive and negative effects on Alzheimer’s. Metabolic issues, exacerbated by a lack of exercise and a poor diet, have also been linked to Alzheimer’s and cognitive decline.3

Both high and low body weight lead to an increased risk of cognitive impairment and Alzheimer’s. Doctors think that a diet high in fish, fruit, and vegetables can help protect against Alzheimer’s or slow its progression. Eating a well-balanced diet is key.3

Physical and mental exercise also promotes brain health. People of all ages who engage in learning, reading, playing games, or other cognitively stimulating activities are less likely to develop dementia in general.3

Scientists are actively researching what contributes to, or helps to slow, the progression of Alzheimer’s. Consult with your care team before making changes to diet or exercise to determine what is best for your body and mind.4

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