How to Protect Your Brain Throughout Life and Reduce Dementia Risk

– 45% of dementia cases could be prevented by addressing 14 modifiable risk factors (Lancet, 2024).
– Prevention is a dynamic, lifelong process (childhood, midlife, and older adulthood).
– Protecting the brain means not only reducing risks but also building cognitive reserve through stimulation and social participation.

Dementia prevention and risk factors

When we think about preventing dementia, it is easy to imagine a conversation that begins in older adulthood, perhaps when the first memory lapses appear. However, current evidence points to a much broader perspective. 

The 2024 Lancet Commission identifies 14 potentially modifiable risk factors and estimates that addressing them across the life course could prevent or delay around 45% of dementia cases (Livingston et al., 2024). These factors include:

• lower educational attainment, 
• hearing loss, 
• hypertension, 
• high LDL cholesterol, 
• obesity, 
• smoking, 
• depression, 
• physical inactivity, 
• diabetes, 
• excessive alcohol consumption, 
• traumatic brain injury, 
• social isolation, 
• air pollution, 
• and untreated vision loss.

However, calling these factors “modifiable” does not mean that they all depend exclusively on individual choices or can be changed equally easily. Bransby et al. (2024) specifically highlight the need to consider how modifiable each factor really is and what barriers—social, economic, environmental, or health care-related—may limit that possibility. That is why dementia prevention is better understood as a trajectory shaped over decades than as a list of behaviors a person must follow perfectly.

Moreover, protecting the brain is not only about reducing harmful exposures. It also means building resources that can help people better cope with changes associated with aging and disease. In this regard, a systematic review and meta-analysis of cognitive reserve across the life course found that higher levels of reserve were associated with a lower subsequent risk of dementia. Education was particularly important in the earlier stages of life, while cognitive activity and social connection became more prominent at later ages (Liu et al., 2024).

Dementia prevention starts decades before the first symptoms

Rather than asking only what an older adult can do to reduce their dementia risk, we should start by asking what the brain needs to stay protected at each point in life. 

For example, data from the Framingham Heart Study show that the relationship between potentially modifiable factors and subsequent dementia risk varies by life stage. Hwang et al. (2023) observed particularly strong associations for diabetes and physical inactivity in midlife, as well as a higher risk when several factors accumulated.

The Lancet Commission takes the same perspective. Livingston et al. (2024) place education in the early stages of life, give substantial weight to vascular, metabolic, and behavioral factors during midlife, and highlight others, such as social isolation and vision loss, in later life. This does not mean that each factor belongs exclusively to a particular age; rather, there are windows of opportunity when certain interventions may be especially important.

Childhood and adolescence: building a brain with resources

During childhood and adolescence, the brain undergoes a long process of development, knowledge acquisition, and skill consolidation. Moceri et al. (2000) proposed that certain conditions in the early years could be related to later risk of Alzheimer’s disease. In their community-based case-control study, they found associations between certain characteristics of the environment before age 18 and the later development of the disease. Because of its observational design and age, these data cannot establish causality, but they helped introduce the idea that brain health history can begin long before adulthood.

Recent evidence supports this possibility, although it must be interpreted cautiously. Abouelmagd et al. (2025) analyzed nine studies with more than 283,000 participants and found an association between cumulative exposure to adverse childhood experiences and a higher subsequent risk of dementia. Childhood maltreatment was also significantly associated with risk. However, the authors themselves rated the certainty of the evidence as low or very low because retrospective studies predominated, methods for measuring adverse experiences differed, and other methodological limitations were present. Therefore, these experiences should be understood as possible vulnerability factors, not as direct causes or inevitable predictors of dementia.

Perhaps the most useful approach is not to think of an early experience as being irreversibly “imprinted” on the brain, but to understand how it may influence later stages of life. In a cohort of 17,412 older Japanese adults, Tani et al. (2020) observed that having experienced three or more adverse events before age 18 was associated with a higher subsequent risk of dementia. Part of that relationship was mediated by adult-life variables such as socioeconomic circumstances, social relationships, smoking, depression, and health status. In other words, an early factor may help shape other risk factors that emerge decades later.

At the same time, education is one of the most widely studied indicators of cognitive reserve. The review by Liu et al. (2024) found that greater cognitive reserve in the early stages of life, particularly through education-related indicators, was associated with a lower risk of dementia. Rather than viewing schooling as absolute protection, we can understand it as an opportunity to develop knowledge, strategies, and skills that provide a foundation for continued learning later on.

Adulthood and midlife: protecting what we have built

As we move into adulthood, the focus of prevention begins to shift. Learning, maintaining relationships, and staying cognitively active remain important, but protecting the brain from vascular and metabolic exposures sustained over many years becomes increasingly important. A review of 34 prospective cohorts found that factors such as obesity, diabetes, hypertension, hypercholesterolemia, and smoking in midlife were associated with a higher subsequent risk of dementia (Li et al., 2019).

This relationship between cardiometabolic health and brain health also appears in very large population-based studies. Using data from around half a million adults in China, Bueno Lopez et al. (2025) found that a history of conditions such as hypertension, diabetes, and stroke was associated with a higher subsequent risk of dementia and indicators of brain atrophy. Because this was an observational study, we cannot conclude that controlling a single condition will prevent dementia, but the findings underscore the importance of caring for vascular and metabolic health long before cognitive symptoms appear.

Cumulative exposure also seems to matter. Among more than 203,000 UK Biobank participants, Tai et al. (2022) observed a progressive increase in dementia risk as stroke, diabetes, and myocardial infarction accumulated. The presence of multiple cardiometabolic conditions was also associated with lower hippocampal and gray matter volumes and a greater burden of white matter hyperintensities.

Therefore, a single measurement may tell only a small part of the story. Hwang et al. (2023) found that the accumulation of different factors in midlife and later stages was associated with a higher risk of dementia. From a prevention perspective, it is useful to consider how long a person has had diabetes, how their blood pressure has changed over time, how many years they have smoked, or what role physical activity has played throughout their life.

This does not mean that there are universal targets for dementia prevention. Medical recommendations regarding blood pressure, diabetes, or cholesterol should be tailored to each person’s characteristics and needs. From a brain health perspective, what matters is that Livingston et al. (2024) include management of these factors as part of a prevention strategy that begins long before cognitive decline appears.

Older adulthood: keep protecting the brain and staying connected

Reaching older age does not mean the window for prevention has closed. Physical activity, cardiovascular health, and other habits maintained throughout life remain important at this stage, while factors that can change how a person interacts with their environment also take on greater importance. 

Hearing loss is one of these factors. A recent systematic review examined its relationship with cognitive decline and explored the possible role of social isolation as an intermediary mechanism, although the evidence does not yet allow researchers to determine precisely how much this pathway explains (Dhanda et al., 2024).

Social and cognitive engagement are also important at this stage. In the meta-analysis by Liu et al. (2024), cognitive activity and social connection in older age were associated with a lower incidence of dementia. This does not mean that reading, completing exercises, or taking part in a specific activity can guarantee that someone will not develop a neurodegenerative disease, but continuing to learn, connect with others, and participate in mentally stimulating activities is an important part of a life course associated with greater cognitive reserve.

Vision is another example. Untreated vision loss was one of the two new factors added by the Lancet Commission in 2024, along with high LDL cholesterol. Livingston et al. (2024) thus highlight the importance of addressing sensory impairments as part of risk-reduction strategies. Being able to see and hear well is not only about receiving sensory input; it also makes it possible to read, communicate, move around more independently, and participate in everyday activities.

The relationship between the senses, social participation, and cognition appears to be complex. In a study of 6,799 adults, Wu and Zhou (2024) observed that social isolation explained a small part of the association between hearing impairment and poorer cognitive functioning. Most of the relationship remained unexplained by this pathway, reminding us that dementia risk factors rarely operate in isolation or through a single mechanism.

Life stage	Risk/vulnerability factors	Protective factors: building reserve	Brain impact and evidenced mechanism
Early life (<18 years)	– Lower educational attainment. – Adverse childhood experiences and childhood maltreatment. – Three or more accumulated adverse experiences before age 18.	Formal education as an opportunity to develop knowledge, strategies, and skills.	An early factor may shape other risk factors (socioeconomic circumstances, depression, smoking) that emerge decades later (Tani et al., 2020; Abouelmagd et al., 2025).
Midlife (18–65 years)	– Vascular and metabolic factors: obesity, diabetes, hypertension, and hypercholesterolemia (high LDL cholesterol). – Behavioral factors: smoking, physical inactivity, and excessive alcohol consumption. – Medical history: traumatic brain injury, stroke, and myocardial infarction.	– Staying cognitively active and maintaining social relationships. – Long-term care and management of cardiovascular and metabolic health.	The accumulation of cardiometabolic conditions is associated with lower hippocampal volume, lower gray matter volume, and a greater burden of white matter hyperintensities (Tai et al., 2022; Bueno Lopez et al., 2025; Hwang et al., 2023).
Older adulthood (>65 years)	– Sensory impairments: untreated vision loss and hearing loss. – Social isolation and air pollution.	– Continuing to learn, read, complete exercises, and participate in stimulating activities. – Maintaining physical activity.	Vision and hearing impairments limit independence, communication, and reading, which may partly explain the social isolation associated with cognitive decline (Liu et al., 2024; Dhanda et al., 2024; Wu and Zhou, 2024).

It is not just about reducing risks, but building reserve