How to Protect Your Brain Throughout Life and Reduce Dementia Risk

– 45% of dementia cases could be prevented by addressing 14 modifiable factors (Lancet, 2024).
– Prevention is a dynamic, life-course process (childhood, midlife, and old age).
– Protecting the brain isn’t just about reducing risks but also about building cognitive reserve through stimulation and social participation.

Dementia prevention and risk factors

When we think about preventing dementia, it’s easy to imagine a conversation that starts in old age, perhaps when the first memory lapses appear. However, current evidence offers 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:

• Low 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.

Talking about “modifiable” factors, however, doesn’t mean that they all depend solely on individual decisions or that they can all be changed equally easily. Bransby et al. (2024) specifically warn of the need to consider how modifiable each factor really is and what social, economic, environmental, or healthcare barriers may limit that possibility. That’s why dementia prevention is better understood as a trajectory built over decades than as a list of behaviors a person has to follow perfectly.

In addition, protecting the brain isn’t just about reducing harmful exposures. It also involves building resources that can help us cope better with the changes associated with aging and disease. In this regard, a systematic review and meta-analysis on cognitive reserve across the life course found that higher levels of reserve were associated with a lower subsequent risk of dementia. Education was especially relevant in early life, while cognitive activity and social connection played a bigger role later in life (Liu et al., 2024).

Dementia prevention begins decades before the first symptoms

Instead of only asking what an older person can do to reduce their risk of dementia, we should start by asking what the brain needs to be protected at each stage of life. 

Data from the Framingham Heart Study show, for example, that the relationship between potentially modifiable factors and later dementia risk varies by life stage. Hwang et al. (2023) observed especially relevant 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 considerable weight to vascular, metabolic, and behavioral factors in midlife, and highlight others, such as social isolation or vision loss, in later life. This doesn’t mean that each factor belongs exclusively to one age, but rather that there are windows of opportunity in which certain interventions may be especially relevant.

Childhood and youth: building a well-resourced brain

During childhood and youth, the brain goes through a long process of development, knowledge acquisition, and skill consolidation. Moceri et al. (2000) suggested 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 some characteristics of the environment before age 18 and later development of the disease. Because of its observational design and age, these data don’t allow causality to be established, but they were important in introducing the idea that the history of brain health can begin long before adulthood.

Recent evidence supports this possibility, although it must be interpreted with caution. 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 later risk of dementia. Child maltreatment also showed a significant association. However, the authors themselves rated the certainty of the evidence as low or very low because of the predominance of retrospective studies, differences in how adverse experiences were measured, and other methodological limitations. These experiences should therefore be understood as possible sources of vulnerability, not as direct causes or inevitable predictors of dementia.

Perhaps the most interesting point isn’t that an early experience is irreversibly “recorded” in the brain, but understanding how it can influence later stages. In a cohort of 17,412 older Japanese adults, Tani et al. (2020) found that having experienced three or more adverse experiences before age 18 was associated with a higher later risk of dementia. Part of this relationship was mediated by adult-life variables such as socioeconomic conditions, social relationships, smoking, depression, and health status. In other words, an early factor can help shape other risk factors that appear decades later.

At the same time, education is one of the most studied indicators of cognitive reserve. The review by Liu et al. (2024) found that greater cognitive reserve in early life, especially through education-related indicators, was associated with a lower risk of dementia. Rather than seeing schooling as absolute protection, we can see it as an opportunity to develop knowledge, strategies, and skills on which new learning will later build.

Adulthood and midlife: protecting what we have built

As we move into adulthood, the goal of prevention starts to change. Learning, maintaining relationships, and staying cognitively active remain important, but protecting the brain from vascular and metabolic exposures sustained over 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 later risk of dementia (Li et al., 2019).

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

Accumulation also seems to matter. In 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 several cardiometabolic conditions was also associated with lower hippocampal and gray matter volume and a greater burden of white matter hyperintensities.

That’s why 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’s worth looking at how long diabetes has been present, how blood pressure has changed over time, how many years someone has smoked, or what role physical activity has played throughout life.

This doesn’t mean there are universal figures for preventing dementia, either. Medical recommendations on blood pressure, diabetes, or cholesterol should be tailored to each person’s characteristics and needs. What matters from a brain health perspective is that Livingston et al. (2024) include controlling these factors as part of a prevention strategy that begins long before cognitive decline appears.

Old age: continuing to protect the brain and keep it connected

Reaching old age doesn’t mean the window for prevention has closed. At this stage, physical activity, cardiovascular health, and other lifelong habits remain important, but factors that can change how a person interacts with their environment also take center stage. 

Hearing loss is one of them. A recent systematic review analyzed its relationship with cognitive decline and explored the possible role of social isolation as an intermediate mechanism, although the evidence doesn’t yet allow us to determine precisely how much this pathway explains (Dhanda et al., 2024).

Social and cognitive participation is also part of this stage. In the meta-analysis by Liu et al. (2024), cognitive activity and social connection in later life were associated with a lower incidence of dementia. This doesn’t mean that reading, doing exercises, or taking part in a specific activity can guarantee that a person won’t develop a neurodegenerative disease, but continuing to learn, socialize, and take part in mentally stimulating activities is part of a trajectory 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 deficits as part of risk-reduction strategies. Seeing and hearing well isn’t just about receiving sensory input; it also means being able to read, communicate, get around more independently, and take part in everyday activities.

The relationship between the senses, social participation, and cognition seems to be complex. In a study of 6,799 adults, Wu and Zhou (2024) found 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, a reminder that dementia risk factors rarely work 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)	– Low educational attainment. – Adverse childhood experiences and child maltreatment. – Accumulation of three or more adverse experiences before age 18.	Formal education as an opportunity to develop knowledge, strategies, and skills.	An early factor can shape other risk factors (socioeconomic, depression, smoking) that appear 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). – Behavioral factors: smoking, physical inactivity, and excessive alcohol consumption. – Medical history: traumatic brain injury, stroke, and myocardial infarction.	– Staying cognitively active and nurturing social relationships. – Long-term care and control 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).
Old age (>65 years)	– Sensory deficits: untreated vision loss and hearing loss. – Social isolation and air pollution.	– Continuing to learn, read, do exercises, and take part in stimulating activities. – Staying physically active.	Visual and hearing deficits 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’s not just about reducing risks but about building reserve