The 14 Modifiable Risk Factors for Dementia

By Shannon Kasun, Neuroscience Specialist

For a long time, dementia was considered an unfortunate, almost inevitable consequence of growing older. Age and genetics were thought to largely determine who would develop the disease, leaving little room for prevention. But over the past several decades, our understanding of dementia has changed considerably. Research increasingly suggests that our brain health is influenced by much more than the number of candles on our birthday cakes or the genes we inherit from our parents.

In 2024, the Lancet Standing Commission on Dementia Prevention, Intervention, and Care published a report identifying 14 potentially modifiable risk factors that, together, may account for approximately 45% of dementia cases worldwide (Livingston et al., 2024). In other words, the Commission estimated that nearly half of dementia cases could theoretically be prevented or delayed by addressing these factors. Of course, this does not mean that eliminating these risks guarantees a dementia-free life, or that any one individual can reduce their risk by 45%. Rather, the estimate reflects the potential impact of addressing these factors across an entire population.

Perhaps most interestingly, the report suggests that dementia prevention is not something we should begin thinking about when we turn 65. Many of the biological processes contributing to cognitive decline develop over decades, and the factors that influence them change throughout our lives. 

The Commission organized these 14 risk factors into three stages of life: early life, midlife, and late life. Let's take a closer look at what they identified and why these factors may matter for the aging brain.

Early Life: Building the Foundation

1. Less Education

Our brains are remarkably adaptable. Throughout our lives, they respond to our experiences, strengthening and reorganizing neural connections as we learn new information and develop new skills. Education, particularly during childhood and adolescence, is thought to contribute to something called cognitive reserve. This refers to the brain's ability to maintain cognitive functioning despite age-related changes or neurological damage.

Consider two individuals with similar levels of Alzheimer's-related pathology in their brains. One may exhibit noticeable cognitive impairment, while the other continues to function relatively normally. Differences in cognitive reserve may help explain why.

The Commission identified lower educational attainment as a risk factor for dementia, emphasizing the importance of access to quality education early in life. Although we cannot go back and change our childhood education, opportunities for learning and cognitive enrichment continue throughout adulthood.

Midlife: More Than Just Heart Health

Many of the risk factors identified by the Commission become particularly relevant during midlife. Interestingly, several are conditions we typically associate with cardiovascular or metabolic health rather than brain health. This overlap is not coincidental. The brain is an extraordinarily metabolically demanding organ, relying on a continuous supply of oxygen and nutrients to function properly. Conditions that compromise vascular health, metabolism, or inflammatory regulation can therefore have consequences that extend well beyond the rest of the body.

2. Hearing Loss

Hearing loss may seem like an unlikely contributor to dementia, but it is one of the largest potentially modifiable risk factors identified by the Commission. Researchers have proposed several explanations for this relationship. When hearing becomes impaired, the brain must devote additional resources to processing auditory information, potentially leaving fewer resources available for other cognitive tasks. Hearing loss can also make conversations more difficult, leading some individuals to withdraw from social activities.

Over time, reduced auditory stimulation and social engagement may contribute to changes in cognitive functioning. Although researchers are still working to understand these mechanisms, addressing hearing impairment is an important consideration for healthy aging.

3. High LDL Cholesterol

High LDL cholesterol was one of two new risk factors added to the Commission's 2024 report. LDL cholesterol is commonly referred to as "bad cholesterol" because elevated levels contribute to atherosclerosis, the accumulation of fatty deposits within blood vessels. As these deposits develop, they can restrict blood flow and increase the risk of cardiovascular and cerebrovascular disease. 

Although we often discuss cholesterol in the context of heart attacks and strokes, the health of our blood vessels is equally important for the brain. The Commission estimated that elevated LDL cholesterol in midlife may account for approximately 7% of dementia cases worldwide.

4. Depression

Depression and dementia have a complicated relationship. On one hand, depression may contribute to dementia risk through changes in stress physiology, inflammatory signaling, sleep, and health behaviors. On the other hand, depressive symptoms can sometimes emerge during the early stages of neurodegenerative disease, raising questions about whether depression is a cause, consequence, or early indicator of dementia. The relationship is likely not explained by a single mechanism. Nevertheless, the association highlights the importance of considering psychological well-being alongside physical health when discussing cognitive aging.

5. Traumatic Brain Injury

Unlike many other risk factors, traumatic brain injury (TBI) can introduce neurological damage relatively suddenly. A significant blow to the head can damage neurons, disrupt connections between brain regions, and initiate inflammatory processes. Depending on the severity of the injury, some of these changes may persist long after the initial trauma.Moderate and severe TBIs, as well as repeated head injuries, have been associated with an increased risk of dementia later in life. This makes preventing head injuries, whether through fall prevention, protective equipment, or safer recreational activities, an important part of protecting long-term brain health.

6. Physical Inactivity

We often think of exercise as something we do for our muscles, bones, or cardiovascular system, but the benefits extend to the brain. Physical activity influences several processes involved in maintaining healthy neural functioning, including cerebral blood flow, metabolic regulation, inflammation, and neuroplasticity. In fact, a study by Erickson and colleagues (2011) found that older adults who participated in moderate-intensity aerobic exercise three times per week for one year experienced an approximately 2% increase in hippocampal volume. The hippocampus, a brain structure essential for memory, is particularly vulnerable to Alzheimer's disease. This increase effectively offset an estimated one to two years of age-related hippocampal volume loss.

Exercise is especially interesting because it may influence several dementia risk factors simultaneously. Regular physical activity can help regulate blood pressure, improve insulin sensitivity, support mental health, and reduce excess adiposity.

7. Diabetes

Diabetes, particularly type 2 diabetes, is associated with an increased risk of dementia. Chronically elevated blood glucose and insulin resistance can contribute to vascular damage, oxidative stress, and inflammation. These processes may compromise the health of the brain's blood vessels and interfere with normal cellular functioning. Researchers are also investigating how disruptions in insulin signaling and glucose metabolism may contribute to neurodegenerative processes.

This relationship illustrates an important point: the brain does not operate independently of the rest of the body. Our metabolic health can have meaningful consequences for cognitive functioning.

8. Smoking

Smoking has well-established consequences for cardiovascular and respiratory health, but its effects on the brain are sometimes overlooked. Tobacco smoke contains chemicals that contribute to oxidative stress, inflammation, and damage to blood vessels. Over time, these changes can compromise the vascular system responsible for supplying the brain with oxygen and nutrients. Smoking cessation is associated with numerous health benefits, and evidence suggests that quitting may also help reduce dementia risk.

9. Hypertension

High blood pressure is another example of the close relationship between cardiovascular and cognitive health. The brain contains an extensive network of small blood vessels responsible for delivering oxygen and nutrients to billions of neurons. When blood pressure remains elevated over time, these vessels can become damaged, contributing to reduced vascular function, white matter abnormalities, and an increased risk of stroke. Importantly, these changes can begin long before someone experiences noticeable cognitive difficulties.

The Commission emphasizes the importance of identifying and treating hypertension during midlife, rather than waiting until later adulthood when vascular damage may already have accumulated.

10. Obesity

Obesity during midlife has also been associated with an increased risk of dementia. Excess adipose tissue, particularly visceral fat surrounding internal organs, can contribute to chronic low-grade inflammation, insulin resistance, and cardiovascular dysfunction. 

Body weight alone does not tell the entire story. Body composition, including the relative amounts and distribution of fat and skeletal muscle, can provide additional information about metabolic health. This distinction is particularly relevant as we age, when changes in muscle mass and fat distribution can occur even without substantial changes in body weight.

11. Excessive Alcohol Consumption

Although alcohol is deeply embedded in many social traditions, excessive consumption can have consequences for the aging brain. Chronic heavy alcohol use can damage neurons, disrupt communication between brain regions, contribute to nutritional deficiencies, and increase the risk of vascular disease.

The Commission identifies excessive alcohol consumption as a modifiable dementia risk factor. Reducing heavy drinking may therefore represent another opportunity to protect long-term cognitive health.

Late Life: The Importance of Our Environments and Relationships

The final three risk factors are particularly interesting because they draw attention to influences that extend beyond our traditional understanding of health behaviors.

Our cognitive health is not determined solely by what we eat, how much we exercise, or whether we develop certain medical conditions. It is also shaped by the environments in which we live, the sensory information we receive, and the people with whom we interact.

12. Social Isolation

Humans are inherently social. Throughout our lives, relationships provide opportunities for conversation, emotional support, shared experiences, and cognitive stimulation. Social isolation, however, has been associated with an increased risk of dementia.

There are several possible explanations for this relationship. Social interaction requires us to engage a variety of cognitive processes, including attention, memory, language, and emotional regulation. Relationships may also influence stress physiology, mental health, and the behaviors we adopt in our everyday lives. Interestingly, social isolation is not necessarily the same as loneliness. Someone can spend considerable time alone without feeling lonely, while another person may feel disconnected despite being surrounded by people.

13. Air Pollution

Air pollution may be one of the less obvious risk factors on this list. Fine particulate matter, commonly referred to as PM2.5, consists of microscopic particles small enough to penetrate deep into the lungs and contribute to systemic physiological effects. Research has associated long-term exposure to air pollution with increased dementia risk. Proposed mechanisms include oxidative stress, systemic and neuroinflammation, and vascular dysfunction.

Unlike some other risk factors, air pollution is not entirely within an individual's control. Exposure depends on where we live, work, and spend our time, making environmental policies and community-level interventions particularly important. Nevertheless, strategies such as monitoring air quality, limiting exposure during periods of heavy pollution, and improving indoor air filtration may help reduce exposure.

14. Untreated Vision Loss

Untreated vision loss was the second new risk factor added to the 2024 report. Like hearing loss, visual impairment may influence cognitive health through changes in sensory stimulation, social engagement, and independence. For example, someone experiencing deteriorating vision may gradually stop driving, reading, participating in hobbies, or attending social gatherings. These changes can reduce opportunities for both cognitive and social engagement.

The Commission highlights the importance of identifying and treating vision impairments when possible, including through corrective lenses and cataract treatment.

Looking Ahead

The Lancet Commission's findings offer an important perspective on dementia prevention. Although age remains the strongest risk factor for dementia, growing older does not necessarily mean that cognitive decline is inevitable. Nor does having a family history of Alzheimer's disease mean that our cognitive futures are predetermined.

There is still much we do not understand about why some individuals develop dementia while others remain cognitively healthy well into their 80s, 90s, and beyond. But research increasingly suggests that the conditions we experience throughout our lives can influence these outcomes. Perhaps the most important takeaway is that dementia prevention does not begin when memory problems appear. It begins much earlier, through the cumulative influence of our health, behaviors, relationships, and environments. And while we cannot control every factor that influences our brains, understanding the ones we can modify gives us an opportunity to support cognitive health throughout the aging process.

References

Livingston, G., Huntley, J., Liu, K. Y., et al. (2024). Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. The Lancet, 404(10452), 572–628.

Erickson, K. I., Voss, M. W., Prakash, R. S., et al. (2011). Exercise training increases size of hippocampus and improves memory. Proceedings of the National Academy of Sciences, 108(7), 3017–3022.