Risk factors for dementia

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When it comes to dementia, there are risk factors you can change, and risk factors you cannot. Learn about both types on this page, as well as unproven risks that need more evidence to be considered valid.

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Now that you know what the risk factors are, find out more about maintaining a healthy lifestyle and brain.

Do you have more questions? Contact your local Alzheimer Society.

What are risk factors?

Risk factors are characteristics of your lifestyle, environment and genetic background that increase your likelihood of getting a disease.

Risk factors are not causes of disease on their own. Instead, they represent an increased chance – not a certainty – that a disease such as dementia will develop.

At the same time, having little or no exposure to known risk factors does not necessarily protect you from developing the disease.

There are some risk factors that can be changed, and some that cannot – read on to know which are which!

Risk factors that can be changed

High blood pressure

People who have high blood pressure or hypertension in mid-life are on average more likely to develop dementia compared to those with normal blood pressure.

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Smoking

Smokers are 45% more likely to develop Alzheimer’s disease compared to non-smokers or ex-smokers.

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Diabetes

On average, people with Type 2 diabetes are twice as likely to develop dementia compared to those without diabetes.

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High cholesterol

People with high cholesterol levels in mid-life are more likely to develop dementia compared to those with normal cholesterol.

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Obesity and lack of physical activity

Obesity and lack of physical activity increase the risk of developing diabetes and high blood pressure. Obesity in mid-life is also a risk factor for dementia.

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Poor diet

An unhealthy diet, high in saturated fat, sugar and salt, can increase the risk of developing many illnesses including Type 2 diabetes, cardiovascular disease and dementia.

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High alcohol consumption

People who drink excessively have the highest risk of dementia compared to people who drink moderately or not at all.

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Low levels of formal education

People who actively use their brains throughout their life may be building a ‘cognitive reserve’ that can provide more protection against brain cell damage caused by dementia.

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Depression

Many researchers believe that depression is a risk factor for dementia, whereas others believe it may be an early symptom of the disease, or both.

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Head injuries

Experiencing severe or repeated head injuries increases a person’s risk of developing dementia.

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Hearing loss

It’s still unclear how exactly hearing loss increases the risk of dementia, but it can lead to social isolation, loss of independence and problems with everyday activities.

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Social isolation

Besides dementia, social isolation can also increase the risk of hypertension, coronary heart disease and depression.

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Living near busy roads

The impact on the brain from vehicle pollution is still being studied by researchers, but it’s estimated that people who live within 50 metres of a busy road are more likely to develop dementia.

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Risk factors that cannot be changed

Age

Dementia is not a normal part of aging. However, age is the strongest known risk factor for dementia. The older you become, the higher the risk:

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  • One in 20 Canadians over age 65 has Alzheimer’s disease.
  • After 65, the risk of developing Alzheimer’s disease doubles approximately every five years, with one in four Canadians over 85 having Alzheimer’s disease.

While rare, dementia can affect people under 65. This is known as young-onset dementia.

Sex and gender

Women have a higher risk of developing Alzheimer’s disease than men. While the reasons for this are still unclear, some of the potential contributors include women living longer on average than men and changes in estrogen levels over a woman’s lifetime.

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For types of dementia other than Alzheimer’s, men and women have the same risk.

For more information on how women may have different risks for dementia than men, watch this brainXchange webinar on understanding sex and gender differences in the brain.

Genetics

We don’t yet fully understand the role of genes in the development of dementia. We do know that most cases of Alzheimer’s disease are sporadic, meaning they do not run in families. Only rare instances of Alzheimer’s disease are inherited or familial, accounting for 2-5% of all cases.

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Scientists have found over 20 genes that may increase the risk of developing Alzheimer’s disease. Three of these genes directly cause Alzheimer’s disease: PSEN1, PSEN2, and APP.

If a person has an alteration in any of these genes they will almost certainly develop familial Alzheimer’s disease, often well before the age of 65. If a parent has any of these faulty genes, their children have a 50% chance of inheriting the disease.

The other genes associated with Alzheimer’s disease increase the risk, but don’t guarantee that Alzheimer’s disease will develop.

Check out our page on Genetic testing and Alzheimer's disease for more information.

Unproven risks

Some factors are alleged to cause dementia, but these claims have not been backed up with strong evidence. For them to be considered as valid risk factors, more studies need to be done that show conclusive links.

Here's what we currently know about these unproven risks for dementia:

Aluminum

Current research provides no convincing evidence that exposure to trace elements of aluminum is connected to the development of dementia.

Aluminum has been studied for over 40 years as a substance that might be linked to dementia. However, there have been many conflicting findings.

  • Some studies show increased levels of trace elements of aluminum in the brains of people with dementia, while others do not.
  • Studies have not found an increased incidence of dementia in people with occupational exposure to aluminum.
  • Tea is one of the few plants whose leaves accumulate larger trace element amounts of aluminum that can seep into the brewed beverage. However, there is no evidence that dementia is more prevalent in cultures that typically drink large amounts of tea.
  • Unfortunately, earlier animal studies focused on one animal that is particularly susceptible to aluminum poisoning, which has led to incorrect conclusions about the general effects of aluminum on the body.

Aluminum in cookware and other products

It would be difficult to significantly reduce exposure to aluminum simply by avoiding the use of aluminum products such as pots and pans, foil and beverage cans.

That's because the use of aluminum in these products only contributes to a very small percentage of the average person's intake of aluminum. It's important to remember that aluminum is an element found naturally in the environment and our bodies at levels that are normal and not harmful.

Aluminum in the environment

Aluminum has a non-metallic form that makes up eight per cent of the earth's surface. In small amounts, aluminum is referred to as "trace elements", and occur naturally in the foods we eat, in our drinking water and are even added to the water treatment process in some municipalities.

Trace elements of aluminum may also be found in:

  • Many processed foods
  • Cosmetics and personal hygiene products, such as deodorants and nasal sprays
  • Some drugs in order to make them more effective or less irritating
  • The air we breathe from dry soil, cigarette smoke, pesticide sprays and aluminum-based paint.

Aluminum in our bodies

Aluminum is also found naturally in our bodies, but its role is not fully understood. Very little of the aluminum taken in by a healthy individual is actually absorbed; most of it is flushed out by the kidneys.

More useful links and resources

https://archive.alzheimer.ca/sites/default/files/files/national/research/research_risk-factors.pdf

Risk factors. Alzheimer Society of Canada, 2018. Read about risk factors for dementia in our downloadable, print-friendly infosheet. This sheet also contains strategies and lifestyle changes that can help you reduce your risk of developing dementia.

https://archive.alzheimer.ca/sites/default/files/files/national/research/research_understanding-genetics-and-alzheimers-disease.pdf

Understanding genetics and Alzheimer's disease. Alzheimer Society of Canada, 2018. In our downloadable, print-friendly infosheet, learn more about the role that genetics plays as a risk factor for dementia, and find out whether you should pursue genetic testing.

https://www.alzheimers.org.uk/about-dementia/risk-factors-and-prevention?documentID=102

Risk factors and prevention. Alzheimer's Society UK. This comprehensive webpage from the Alzheimer's Society UK has some helpful nuggets of research and advice related to reducing your risk of dementia.

https://apps.who.int/iris/bitstream/handle/10665/128041/WHO_NMH_PND_CIC_TKS_14.1_eng.pdf;jsessionid=EC9695A1051A365556231979C468C506?sequence=1

Tobacco use and dementia. World Health Organization (WHO), 2014. This report from the WHO details the evidence behind smoking tobacco as a risk factor for dementia.

https://vimeo.com/268998912

Women and Dementia: Understanding sex/gender differences in the brain. brainXchange, 2018. This webinar discusses understandings of sex and gender, sex differences in Alzheimer’s disease, how the higher number of women with Alzheimer's may be due to both, and a discussion of the role of estrogen in the health of brain regions associated with Alzheimer’s disease. In partnership with the Alzheimer Society of Canada and the Canadian Consortium of Neurodegeneration in Aging (CCNA).

https://www.alz.co.uk/research/world-report-2014

World Alzheimer Report 2014: Dementia and Risk Reduction. Alzheimer's Disease International (ADI), 2014. This is the most recent report from ADI that critically examines the evidence for the existence of modifiable risk factors for dementia.