Are There Ways To Prevent Dementia?

As we age, it’s common to worry about the possibility of developing dementia. While aging is the greatest risk factor for dementia, it’s much more complicated than that—there are many causes of dementia and many risk factors associated with its development.

Around the globe, researchers have banded together to identify risk factors and explore methods to prevent dementia. While there is currently no definitive way to prevent dementia, there is strong evidence to suggest several aspects of healthy living may reduce your risk of developing dementia.

Potential Ways To Prevent Dementia

According to the 2020 Lancet Commission on dementia prevention, intervention, and care, three new potentially modifiable risk factors have been identified: excessive alcohol consumption, air pollution, and traumatic brain injury. With this, there are now 12 potentially modifiable risk factors for dementia. Their life-course model of dementia prevention includes one early life risk factor, five midlife risk factors, and six later life risk factors. Together, these risk factors are believed to account for approximately 40% of worldwide dementia cases. In other words, modifying these 12 risk factors may prevent or delay up to 40% of dementia cases.

Early life risk factors are believed to impact cognitive reserve, the brain’s ability to make thicker connections between brain areas and cope with, or moderate, the clinical consequences of a disease. Midlife and later life risk factors are believed to play a role in age-related cognitive decline and may trigger neuropathological changes in the brain.

Taking steps throughout all stages of life to modify risk factors and protect brain health may help prevent dementia.

Potential Risk Factors for Dementia During Early Life

During early life (younger than 45 years), education is the primary factor that is believed to contribute to dementia risk. You can think about education as the foundation for cognitive reserve to be built upon. Higher educational attainment may increase cognitive reserve while lower educational attainment may decrease cognitive reserve. Accordingly, higher educational attainment is associated with a lower risk of dementia while lower educational attainment is associated with a higher risk of dementia. 

Modifying this risk factor by increasing educational attainment at a global scale could prevent or delay 7% of dementia cases.

Potential Risk Factors for Dementia During Midlife

During midlife (45-65 years), there are five potentially modifiable risk factors associated with dementia development: hearing loss, traumatic brain injury (TBI), hypertension, excessive alcohol consumption, and obesity.

• Hearing loss: Hearing loss is believed to account for 8% of worldwide dementia cases, making it the largest known potential modifiable risk factor for dementia. Noise-induced hearing loss is a preventable, and in most cases, treatable condition. Studies have also correlated the use of hearing aids in hearing-impaired individuals with reduced dementia risk.

• TBI: Single, severe TBI—where severe TBI is defined as skull fracture, edema, brain injury, or bleeding—has been linked to widespread hyperphosphorylated tau pathology in both human and animal studies. Consequently, TBI has been linked to Alzheimer’s disease, the most common cause of dementia. TBI is believed to account for 3% of global dementia cases. 

TBI is most commonly caused by falls, motor vehicle crashes, and recreational sports. Taking appropriate safety precautions, such as wearing seatbelts and appropriate headgear, can reduce the risk of TBI.

• Hypertension: Accounting for approximately 2% of global dementia cases, midlife hypertension may contribute to dementia risk. Healthy living—such as eating a heart-healthy diet, regularly exercising, limiting alcohol consumption, quitting smoking, and getting enough sleep—can improve the health of the heart and blood vessels and may reduce the risk of hypertension.
• Excessive alcohol consumption: Excessive alcohol consumption, characterized as drinking more than 21 units of alcohol each week, is a newly identified risk factor that is thought to account for 1% of all dementia cases. Addressing mental illness and implementing substance abuse prevention programs may reduce substance misuse and related harms, including elevated dementia risk.
• Obesity: Obesity, defined as having a body mass index (BMI) of 30 or greater, has been associated with late-life dementia and may be responsible for 1% of dementia cases. Elements of healthy living, such as those mentioned above for hypertension prevention, can help prevent and manage obesity.

Potential Risk Factors for Dementia During Later Life

During later life (older than 65 years), there are six potentially modifiable factors that have been linked to dementia: smoking, depression, physical inactivity, air pollution, and diabetes.

• Smoking: Individuals who smoke cigarettes are at a higher risk of developing dementia. Smoking may account for 5% of global dementia cases. Research has also shown that smokers who quit smoking, even later in life, may benefit from reduced dementia risk. Duration and intensity of smoking, as well as time after smoking cessation, are believed to influence risk. 
• Depression: While depression is often an early symptom of dementia, depression during later life is thought to increase dementia risk, accounting for approximately 4% of worldwide dementia cases. Studies have shown that long-term selective serotonin reuptake inhibitor (SSRI) treatment of depression is associated with delayed progression from mild cognitive impairment (MCI) to clinically diagnosed Alzheimer’s disease.
• Social isolation: Novel social interactions are believed to play an important role in strengthening the cognitive reserve during middle and later life. Less social contact may deplete the cognitive reserve, thus increasing dementia risk. Increased social contact may provide a protective effect against dementia and could delay or prevent dementia in 4% of all cases.
• Physical inactivity: Regular physical activity helps maintain a healthy weight and reduces the risk of cardiovascular conditions, including hypertension and hypercholesterolemia. Physical inactivity has been associated with an elevated risk of dementia and may account for 2% of dementia cases.
• Air pollution: Air pollution is a newly identified potentially modifiable risk factor for dementia, accounting for approximately 2% of dementia cases. Research suggests that airborne particulate pollutants may accelerate neurodegenerative processes. Examples of air pollutants that may increase dementia risk include exposure to high nitrogen dioxide concentrations and particulates from traffic exhaust or wood burning.
• Diabetes: Diabetes is believed to contribute to 1% of dementia cases. Reducing the prevalence of obesity and other conditions associated with diabetes through healthy living can reduce diabetes prevalence and contribute to reduced dementia prevalence. Some studies have shown that long-term glycemic control in those living with diabetes may reduce dementia risk, however, evidence is still limited.

While these risk factors provide compelling evidence that there may be ways to prevent dementia or at least delay its onset, there is a second part of this equation that should be addressed.

Routine testing of cognitive function for all adults—especially those at higher risk of developing dementia—is essential for the early detection of Alzheimer’s and other causes of dementia. This is particularly true as we see promising new treatments and therapies emerge in the drug development pipeline.