Highlights

  • Age, genetics, and family history are risk factors you can't change.
  • The 2024 Lancet Commission identified 14 modifiable risk factors.
  • Together, these may account for around 45 percent of dementia cases.
  • Many risk factors are connected through heart and blood vessel health.

Dementia is one of the most feared conditions of later life. Many people assume it's simply a matter of bad luck or bad genes. But research over the past two decades has revealed a more hopeful picture: while some risk factors are beyond our control, many others can be influenced by the choices we make and the care we receive throughout life.

Understanding the risk factors for dementia is the first step toward protecting your brain. This article explains which factors you can't change, which ones you can, and how risk builds up across a lifetime.

What Is a Risk Factor?

A risk factor is something that increases the likelihood of developing a condition. Having a risk factor doesn't mean you will definitely develop dementia, and not having any doesn't guarantee you won't. Risk factors simply shift the odds.

Dementia usually develops from a combination of factors over many years, not from a single cause.

Risk Factors You Can't Change

Age

Age is the strongest known risk factor. The risk of dementia rises sharply after 65 and roughly doubles every five years after that. However, dementia is not a normal part of aging, and many people live into their 90s and beyond without it.

Genetics

Certain genes affect dementia risk. The best known is APOE e4. Carrying one copy raises the risk of Alzheimer's disease, and carrying two copies raises it more. But many people with APOE e4 never develop Alzheimer's, and many people with Alzheimer's don't carry it.

Rarely, specific gene mutations directly cause early-onset Alzheimer's that runs strongly in families. These account for a very small share of cases.

Family History

Having a parent or sibling with dementia increases risk somewhat, partly due to shared genes and partly due to shared lifestyle and environment.

Sex

More women than men live with dementia. This is partly because women tend to live longer, but researchers are also studying whether hormonal and biological differences play a role.

Down Syndrome

People with Down syndrome have a much higher risk of developing Alzheimer's disease, often at a younger age, because the extra copy of chromosome 21 carries a gene involved in amyloid production.

Risk Factors You Can Influence

In 2024, the Lancet Commission on dementia prevention, intervention, and care, a panel of leading international experts, identified 14 modifiable risk factors. Together, they estimated these factors account for around 45 percent of dementia cases worldwide. That means nearly half of dementia could, in theory, be prevented or delayed.

The Commission grouped these risk factors by the stage of life when they matter most.

Early Life

Less education: Education in childhood and adolescence helps build cognitive reserve, the brain's resilience against damage. Lifelong learning continues to help.

Midlife (Roughly Ages 45 to 65)

  • Hearing loss: One of the largest modifiable risk factors. Untreated hearing loss may increase the brain's workload and reduce social engagement.
  • High LDL cholesterol: Newly added in 2024, high "bad" cholesterol in midlife is linked to increased risk.
  • Depression: Linked with higher dementia risk, and treating it supports brain health.
  • Traumatic brain injury: Head injuries, especially repeated ones, raise risk.
  • Physical inactivity: Regular exercise is strongly linked with lower risk.
  • Diabetes: Poorly controlled blood sugar can damage blood vessels and the brain.
  • Smoking: Damages blood vessels and increases oxidative stress.
  • High blood pressure: Damages small blood vessels in the brain.
  • Obesity: Linked with diabetes, high blood pressure, and inflammation.
  • Excessive alcohol: Drinking more than about 21 units a week is associated with higher risk.

Later Life

  • Social isolation: Loneliness and limited social contact are linked with faster cognitive decline.
  • Air pollution: Long-term exposure to polluted air is associated with greater risk.
  • Untreated vision loss: Newly added in 2024, poor vision may reduce mental stimulation and engagement.

Other Factors Being Studied

Researchers are also looking at:

  • Sleep: Poor sleep and sleep apnea may contribute to brain changes linked with Alzheimer's.
  • Diet: Healthy eating patterns like the Mediterranean and MIND diets are associated with lower risk.
  • Chronic stress: Long-term stress may affect brain health.
  • Cognitive activity: Mentally stimulating activities throughout life appear protective.

Why Risk Factors Add Up

Many risk factors are connected. High blood pressure, diabetes, obesity, smoking, and physical inactivity all affect the heart and blood vessels, which in turn affect the brain. Hearing loss, vision loss, depression, and isolation can reduce mental and social stimulation.

This also works in reverse: improving one area often improves others. Regular exercise, for example, helps control weight, blood pressure, blood sugar, mood, and sleep all at once.

It's Never Too Early or Too Late

Dementia-related brain changes can begin decades before symptoms appear, so midlife is an especially important time to act. But it's never too late to benefit. Studies show that older adults who become more active, socially engaged, and mentally stimulated can still improve their brain health.

Practical Ways to Lower Your Risk

  • Move more: aim for about 150 minutes of moderate activity a week
  • Know your numbers: check blood pressure, cholesterol, and blood sugar regularly
  • Get your hearing and eyes tested, and use aids if needed
  • Don't smoke, and seek help to quit if you do
  • Limit alcohol
  • Protect your head: wear helmets and seatbelts, and reduce fall risks
  • Stay connected with friends, family, and community
  • Keep learning: new skills, languages, hobbies, and brain games all challenge your mind
  • Look after your mental health and seek help for depression
  • Sleep well and get checked for sleep apnea if you snore heavily
  • Eat a brain-healthy diet rich in vegetables, fish, nuts, and whole grains

Understanding Your Personal Risk

It can be helpful to take stock of your own situation. Make a simple list of the risk factors above and note which ones apply to you. Then choose one or two that feel most manageable to work on first. For example, you might book a hearing test, start a daily walk, or ask your doctor to check your blood pressure and cholesterol.

Your doctor can also help you understand your overall risk and create a plan. If you have a strong family history of early-onset dementia, a genetic counselor can explain what testing might show and whether it would be useful for you. For most people, though, focusing on everyday health habits is far more valuable than genetic testing.

Frequently Asked Questions

What is the biggest risk factor for dementia?

Age is the biggest risk factor you can't change. Among modifiable factors, hearing loss and high LDL cholesterol in midlife were among the largest identified by the 2024 Lancet Commission.

Can dementia be prevented?

Not all dementia can be prevented, but experts estimate that nearly half of cases are linked to modifiable risk factors.

If dementia runs in my family, will I get it?

Not necessarily. Family history increases risk somewhat, but lifestyle and health factors also play a major role.

Is it too late to reduce my risk if I'm already older?

No. Healthy changes at any age can benefit brain health.

Key Takeaways

  • Age, genetics, and family history are risk factors you can't change.
  • The 2024 Lancet Commission identified 14 modifiable risk factors.
  • Together, these may account for around 45 percent of dementia cases.
  • Many risk factors are connected through heart and blood vessel health.
  • Healthy changes at any age can help protect your brain.

Your genes are not your destiny. By understanding and addressing the risk factors within your control, you can give your brain the best possible chance of staying healthy and sharp for years to come.

This article provides general educational information and is not medical advice. A qualified healthcare professional can help you evaluate choices in relation to your health history, medications, and individual needs.