Nearly half of all dementia cases worldwide could be prevented or delayed by addressing modifiable risk factors throughout life1 . Dementia risk is influenced by a combination of lifestyle, medical, genetic, and environmental factors, with age remaining the greatest known risk factor2 . Understanding and targeting these risk factors can help reduce the global burden of dementia and improve cognitive health across populations1 .
Modifiable Dementia Risk Factors
Diet and Nutrition
Diet plays a crucial role in brain health and dementia risk. Diets high in saturated fats and cholesterol are linked to an increased risk of Alzheimer's disease and vascular dementia3 . Conversely, diets rich in fruits, vegetables, and omega-3 fatty acids support cognitive function and are associated with a reduced risk of cognitive decline4 . The Mediterranean diet, which emphasizes fruits, vegetables, legumes, whole grains, fish, and olive oil, has been consistently associated with lower dementia risk4 5. This diet also helps reduce conditions such as high blood pressure, high cholesterol, and type 2 diabetes, which are known dementia risk factors5 .
Food insecurity and limited access to healthy foods disproportionately affect disadvantaged populations, contributing to higher dementia risk in these groups6 7. Additionally, diets high in processed foods increase the risk of type 2 diabetes and cardiovascular disease, both of which elevate dementia risk4 .
Hypertension
High blood pressure (hypertension) is a major modifiable risk factor for dementia, particularly vascular dementia3 1. Managing blood pressure, especially in midlife, is critical for reducing dementia risk. The Lancet Commission recommends aiming for a systolic blood pressure of 130 mm Hg or lower from around age 40 to delay or prevent dementia1 . Hypertension increases the risk of stroke and brain vascular damage, which can accelerate cognitive decline3 .
Effective blood pressure control through lifestyle changes and medication can reduce the risk of dementia, highlighting the importance of cardiovascular health in brain aging3 8.
Sleep
Sleep quality and duration are important for maintaining cognitive health. Although specific evidence linking sleep interventions to dementia prevention is limited, poor sleep is associated with cognitive decline and may contribute to dementia risk4 7. Maintaining seven to eight hours of sleep per night supports brain health and may reduce the risk of cognitive impairment2 .
Physical Activity
Physical inactivity is a key modifiable risk factor for dementia4 7. Regular physical activity, particularly aerobic exercise, has a small but beneficial effect on maintaining normal cognition and may help delay mild cognitive impairment1 . Sustained exercise in midlife and later life protects against dementia, possibly by reducing obesity, diabetes, and cardiovascular risk factors1 .
The World Health Organization recommends at least 150 minutes of moderate-intensity physical activity per week to support overall health and cognitive function7 . Staying physically active also helps maintain a healthy weight, which is important for reducing dementia risk2 .
Stress
Chronic stress and depression are linked to increased dementia risk, especially in later life9 4. Late-life depression may be both a risk factor and a symptom of early dementia, complicating the relationship1 . Managing stress through lifestyle interventions and mental health care is important for cognitive health4 7.
Alcohol Use and Smoking
Excessive alcohol consumption is a newly recognized modifiable risk factor for dementia1 . Heavy drinking is associated with brain changes, cognitive impairment, and increased dementia risk1 . Limiting alcohol intake to moderate levels or less can reduce this risk5 .
Smoking is another significant modifiable risk factor. Stopping smoking, even later in life, reduces dementia risk1 . Passive smoking also contributes to cognitive decline, and many countries have implemented policies to reduce exposure1 . Avoiding tobacco use supports vascular and brain health5 .
Diabetes
Type 2 diabetes increases the risk of cognitive impairment and dementia9 4. Managing blood sugar levels is crucial, as higher than normal blood sugar can lead to diabetes and subsequent cognitive decline2 . Although intensive diabetes control has not been shown to reduce dementia risk in clinical trials, maintaining overall metabolic health through diet, exercise, and medication remains important1 .
“We judge that sufficient new evidence supports adding three additional modifiable risk factors for dementia to our 2017 Commission model: excessive alcohol, traumatic brain injury, and air pollution.”
— The Lancet Commission on dementia prevention, intervention, and care1
Non-Modifiable Dementia Risk Factors
“Together the 12 modifiable risk factors account for around 40% of worldwide dementias, which consequently could theoretically be prevented or delayed.”
— The Lancet Commission on dementia prevention, intervention, and care1
Air Pollution
Air pollution is linked to increased risk of cognitive decline and dementia, making it an important environmental risk factor9 10. Fine particulate matter from sources such as wood stoves, forest fires, power plants, factories, and vehicle emissions can penetrate the lungs and enter the bloodstream, affecting multiple organ systems including the brain9 10.
Older adults exposed to high levels of air pollution have a higher risk of vascular dementia and cognitive decline9 10. Children exposed to polluted air may also experience cognitive and cardiovascular problems later in life9 10. Particulate pollution is associated with increased hospitalizations and adverse outcomes in people with dementia9 10.
Historical and ongoing environmental injustices, such as redlining—a discriminatory housing practice—have led to higher exposure to air pollution in communities of color, contributing to health disparities9 10. Addressing these disparities is essential for reducing the overall burden of dementia.
Generational Trauma
While genetics and age are non-modifiable risk factors for dementia, systemic and historical factors like generational trauma influence dementia risk indirectly through social determinants of health9 4. Disparities in dementia risk exist by socioeconomic status and ethnicity, with higher risk in disadvantaged populations11 6. For example, Black Americans have higher rates of early-onset dementia but are less likely to receive timely diagnosis6 7.
Addressing social inequalities and improving access to education, healthcare, and healthy environments can help mitigate some of the risks associated with generational trauma and systemic disadvantage11 6.
Dementia Risk Factors Summary
Dementia risk is influenced by a combination of modifiable and non-modifiable factors. Modifiable risk factors include lifestyle behaviors and medical conditions that can be changed or managed to reduce risk. These include:
- Low education and cognitive inactivity9 1
- Midlife hearing loss9 1
- Obesity and hypertension4 1
- Late-life depression and diabetes9 1
- Physical inactivity and smoking4 1
- Social isolation and excessive alcohol consumption9 1
- Traumatic brain injury and air pollution9 1
Nearly 40% to 45% of dementia cases worldwide could be prevented or delayed by addressing these modifiable factors1 12. Public health policies and individual lifestyle changes targeting these risks are critical for dementia prevention.
Non-modifiable factors such as age, genetics, and environmental exposures like air pollution also contribute to dementia risk but cannot be changed9 4. However, reducing exposure to environmental pollutants and addressing social inequalities can mitigate their impact.
Maintaining cardiovascular health through blood pressure and cholesterol management, adopting a Mediterranean diet, staying physically and socially active, managing chronic conditions like diabetes, and avoiding smoking and excessive alcohol use are key strategies for reducing dementia risk3 475.
| Risk Factor Category | Examples | Impact on Dementia Risk |
|---|---|---|
| Modifiable | Physical inactivity, obesity, hypertension | Up to 40% of dementia cases preventable |
| Non-Modifiable | Age, genetics, environmental exposures | Cannot be changed but impact can be mitigated |
| Emerging Modifiable | Excessive alcohol, traumatic brain injury, air pollution | Newly recognized factors increasing risk |
