Reprinted from The Conversation

Alzheimer’s disease (AD) is on track to become one of the defining public health challenges of our time. Every three seconds, somewhere in the world, someone is diagnosed with dementia, and it’s usually Alzheimer’s disease.

Currently, approximately 50 million people worldwide have AD. By 2050, this number will exceed 130 million.

The human health and socioeconomic consequences of this are going to be immense. But perhaps it doesn’t have to be this way.

Preventing Alzheimer’s

A 2024 report from the influential Lancet Commission suggests that up to one-third of AD cases could be prevented simply by avoiding certain risk factors.

These 14 modifiable risk factors encompass: traumatic brain injury, hypertension, depression, diabetes, smoking, obesity, high cholesterol levels, low physical activity levels, too much alcohol consumption, too little education, vision loss, hearing loss, social isolation and air pollution.

While this comprehensive list is rooted soundly in science, it’s not easy for members of the general public to monitor and manage 14 separate health targets — especially when prevention efforts need to start decades before symptoms appear.

This is a problem that needs addressing. Tackling this problem requires a prevention model that is simple and memorable — something the public can easily embrace, understand and follow.

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There are successful examples that can serve as a template. Stroke prevention associations, for instance, have successfully adopted the FAST (Face, Arm, Speech, Time) mnemonic to teach stroke warning signs. AD prevention needs a FAST equivalent.

Using a SHIELD (Sleep, Head Injury prevention, Exercise, Learning and Diet) may fill that role.

SHIELD brings together the most significant, overlapping dementia risk factors into five core pillars, offering a clear and effective strategy for prevention.

Sleep

Sleep is a foundational element of SHIELD. Maintaining healthy sleep habits is a key protective factor against dementia. Adequate sleep supports brain function, memory, mood and learning.

Insufficient (less than five hours per night) or poor-quality sleep (frequent awakenings), especially in midlife, increases the risk of cognitive decline and dementia. Chronic poor sleep leads to build-up in the brain of amyloid-beta protein, which is implicated in the development of AD.

Poor sleep also increases the likelihood of obesity, high blood pressure and depression, all risk factors for AD. If you’re currently sleeping four to five hours per night, consider changing this habit to avoid increasing your risk for developing dementia in later life. Sleep is a vital tool for brain protection and AD prevention.

Head injury

Head injury prevention is, rather surprisingly, often overlooked in conversations about dementia. There are strong links between traumatic brain injuries, including concussions, and higher AD risk.

Such head injuries can occur in a wide variety of settings, not just professional sports. Intimate partner violence, for example, is unfortunately common in our society and is a frequent, but neglected, cause of head trauma.

Head injury prevention should start early and continue throughout life, as damage can accumulate over time. Broader safety measures (such as improved helmet designs, stronger concussion protocols in youth and adult sports and efforts to prevent head injuries in all settings) can play a significant role in protecting long-term brain health and avoiding AD.

Exercise

Regular movement, even in small amounts, enables better brain aging. (Unsplash/Centre for Ageing Better) Exercise is perhaps the most powerful lifestyle habit for reducing the risk of AD. Exercise directly addresses multiple major risk factors, including obesity, high blood pressure, high cholesterol and depression. It also supports the growth of brain cells, memory and emotional health.

Despite this, physical inactivity remains common, especially in high-income countries, where it may contribute to as many as one in five AD cases. Exercise is not just “heart medicine,” but “brain medicine” too. Regular movement, even in small amounts, enables better brain aging and can help avoid AD.

Learning

Learning, both in and out of school, remains one of the strongest protective factors against dementia. Lower educational levels, such as not finishing secondary school, are linked to a significantly increased risk for dementia. Learning contributes to the brain’s “cognitive reserve,” which is the brain’s ability to function well despite damage or disease.

Individuals with AD maintained better mental function if they had continued learning throughout life. Public health messaging should promote life-long learning in all forms — from reading and language learning to engaging hobbies that keep the brain active. It’s never too early (or too late) to learn another language or to challenge your brain. Boosting your cognitive reserve boosts your brain against AD.

Learning contributes to the brain’s ‘cognitive reserve,’ which is the brain’s ability to function well despite damage or disease. (Unsplash/Val Vesa) Diet Diet also plays a major role in brain health and dementia prevention. No single food prevents dementia. Rather, a combination of nutrient-rich foods supports overall brain health.

Diet

A healthy diet can lower dementia risk by emphasizing whole foods like fruits, vegetables, whole grains, nuts and fish, while restricting processed foods, red meat and sweets.

Adhering to dietary patterns like the Mediterranean diet has shown promising results in protecting against cognitive decline. The Mediterranean diet is a brain/heart-healthy eating style inspired by the traditional diets of people in countries bordering the Mediterranean Sea. It emphasizes plant-based foods with olive oil as the primary fat source, while limiting red meat, processed foods and added sugars.

What we eat influences brain inflammation and brain vascular health — all of which are increasingly tied to AD. A healthy diet shouldn’t feel restrictive or like a punishment for trying to improve brain health. Instead, it can be framed as a positive investment in long-term independence, clarity and energy.

By simplifying the science, the SHIELD framework offers a realistic and research-backed approach to brain health. Until a cure is discovered, prevention is the strongest tool. Concepts like SHIELD provide a starting point for achievable prevention.

Alzheimer’s disease should not be seen as inevitable.

The statistic that there will be more than 130 million people with AD by 2050 must not be accepted as predestined. With the right decisions and actions, we can work towards AD prevention by protecting the minds and memories of millions.

This article is reprinted from The Conversation. Donald Weaver is a Professor of Chemistry and Senior Scientist of the Krembil Research Institute, University Health Network, University of Toronto. Emma Twiss, a fourth year undergraduate student in Life Sciences at Queen’s University, co-authored this story.