What are the Risk Factors and Causes of Alzheimer’s Disease and Other Related Dementias?

Last Updated: May 15, 2019


  Before memories fade, or simple tasks become difficult, or the right words stop coming, or confusion and depression spread across the mind in tandem… before these signs of incurable Alzheimer’s disease become a frightening concern, consider the facts about heredity and preventative lifestyle changes.


Millions of Americans have been diagnosed with Alzheimer’s or some form of dementia. Whether you join them may have more to do with diet and exercise than inherited genetics.


Risk Factors for Developing Dementia

Is dementia inherited? Though rare types of dementia are genetic, meaning they can be inherited by children or grandchildren, the majority of dementia types, including Alzheimer’s, are not considered hereditary. Age, rather than family history, is a much stronger determining factor for Alzheimer’s disease and most forms of dementia. An individual 65 or older has the greatest risk, and according to the Alzheimer’s Association, once a senior has reached 65 years old, the risk for developing Alzheimer’s disease doubles every five years.

Still, knowing your family history is important because rarer forms of dementia (about one in 100 cases) are genetically linked. These include frontotemporal dementia, young-onset Alzheimer’s, Huntington’s disease, and Family Prion disease.


 Confused by Terminology: Do you need a better understanding of what “risk factors” are? How they differ from “causes” and what it means when “dementia has been linked to” something? Read our primer on what these terms mean.


Underlying health issues may increase a person’s potential for dementia, and those health issues can be inherited. They include high blood pressure, diabetes, heart disease and stroke. This is why a healthy lifestyle including smart eating and regular exercise is so important, and why lowering the risk of Alzheimer’s is possible through small-but-beneficial lifestyle changes. (See below.)

Environmental variables might also play a role, and head injuries and brain tumors have been linked to dementia.


  Genetic Testing for Alzheimer’s – Genetic testing (easily taken at home with a saliva swab) can reveal whether a person has a gene or genetic mutation linked to Alzheimer’s disease. A positive result, however, does not mean a person will develop Alzheimer’s. While other dementias are considered hereditary, Alzheimer’s is not. Genetic testing is therefore not definitive.


Causes of Dementia

Dementia comes from damaged nerve cells in the brain. Individuals with dementia are affected differently, depending which part of the brain is damaged. Damaged brain cells cannot communicate with other brain cells normally, affecting thinking, behavior, feelings, memory, and movement.

But what causes dementia?


Neurodegenerative Causes of Dementia

Neurodegeneration is the leading biological cause of dementia, and often leads to Alzheimer’s disease. Neurodegeneration breaks down and kills brain cells (neurons). Over time, dying brain cells cause a permanent and progressive decrease in mental and physical function. Types of dementia that result from neurodegeneration include the following:
Alzheimer’s Disease (AD)
Dementia with Lewy Bodies (DLB)
Frontotemporal Dementias (FTD)
Parkinson’s Disease Dementia (PD)
Huntington’s Disease (HD)


Cerebrovascular Causes of Dementia

Usually the result of strokes, heart disease, and/or hardening of the blood vessels supplying the brain (atherosclerosis), cerebrovascular damage from hemorrhaging, malformation, or blockage is a common biological cause of dementia. Localized areas of the brain are destroyed (so-called “infarcts”) from lack of blood supply (oxygen). The type of dementia that results from cerebrovascular disease is as follows:

Vascular or Multi-Infarct Dementia (VD


Infection-Related Dementia

Infections also cause dementia. Viruses, bacteria, and parasites can destroy brain cells and dementia can result—usually in the later stages of severe infections. Common types of dementia caused by infection include the following:

Creutzfeldt-Jackob Disease (CJD) and other Prion Diseases
Dementia associated with HIV/AIDS


Toxic and Metabolic Causes of Dementia

Dementia can also result from a chemical imbalance in the body caused by a toxin (e.g. drugs), malnutrition, or other biological conditions, such as metabolic disorders. This form of dementia includes the following:
Wernicke-Korsakoff Syndrome (WKS)


Traumatic Causes of Dementia

Serious injuries and concussions to the head and brain are another cause of dementia. This category includes the following dementia:

Traumatic Brain Injury (TBI)


Decrease the Risk of Dementia

While it is not possible to prevent Alzheimer’s disease and other related dementias, there are steps toward decreasing the chances of developing dementia.

Not Smoking
Smoking increases the risk of several illnesses including heart disease and cancer, but it also impacts the brain by affecting blood circulation. Decreased circulation to blood vessels in the brain makes Alzheimer’s or dementia more likely.
There are several ways for someone who wants to quit smoking to get help. Talking to your doctor is a good start. Less-harmful nicotine products like e-cigarette and gum are readily available. The American Cancer society offers extensive tips, links, and a helpline, click here.

Physical activity strengthens the heart, increasing blood circulation. Finding the time and determining which method of exercising works best for you is incredibly important, benefitting mood and overall health. If you have not been very active, start slowly and gradually increase the amount of time you’re moving. Try not to spend too much continuous time sitting.

There are countless helpers throughout local communities and online for people looking to be more active. You could speak with your doctor or go straight to a local gym. Brisk walking outside, even for 10 minutes, elevates the heart rate and increases blood flow. Vigorous aerobic activity like running or biking is huge for health, including brain health. Try to aim for 80 minutes a week of vigorous exercise.

Mind Stimulation
Regularly challenging the mind’s thinking ability has been shown to decrease risk of Alzheimer’s by strengthening brain cells’ ability to cope with illnesses. Try to find something interesting and enjoyable, so the practice becomes habit. Some suggestions:
-Puzzles, like crosswords or sudoku
-Learn an instrument
-Learn another language
-Play card games or board games
-Read regularly
-Take a class, like cooking
-Volunteering in your community, at a school or social center, can be tremendous mental exercise and keeps you socially active.
-Even regular communication—just talking—is beneficial and can help reduce the risk of dementia. Making friends or calling family members keeps you in touch with others and also strengthens mental health.

Eat Healthy
Researchers have determined that a healthy diet can cut a person’s risk of dementia in half by reducing cognitive decline.  “Brain-healthy” foods include:

-Green, leafy vegetables like kale, spinach and broccoli
-Other vegetables (try to eat a salad every day)
-Nuts, for healthy fats, fiber, and antioxidants
-Berries, especially blueberries
-Beans, for fiber and protein
-Whole grains (brown rice, oatmeal, whole-wheat bread and pasta)
-Olive oil

Some foods to limit or outright avoid are red meat, butter or margarine, sweets and anything sugary, cheese, fried foods, and fast food.

A healthy diet doesn’t have to mean changing your life. Even moderate improvements to diet, little changes in how you eat, can have huge long-term benefits. Learn more about reducing your risk of dementia.