Modifiable Risk Factors for Dementia across the Europe: regional comparative studyusing SHARE data

The human brain is not a static organ; it changes throughout life, and for many, those changes eventually lead to dementia, a condition that erodes memory and the ability to function independently. For decades, scientists have known that while some factors like age and genetics cannot be changed, many others can. These "modifiable" risks include things like high blood pressure, smoking, lack of exercise, and social isolation. The prevailing idea in the medical community is that if we can manage these factors, we might prevent a significant portion of dementia cases. However, Europe is a vast continent with deep historical, cultural, and economic differences. A lifestyle or health condition that poses a major threat in one country might be less critical in another, depending on local diets, education systems, and healthcare access. Understanding exactly how these risks play out in different corners of Europe is essential for creating prevention plans that actually work for the people living there.

To uncover these regional differences, researchers led by Matej Kucera and colleagues at Vrije Universiteit Amsterdam turned to a massive, long-running project called SHARE, which tracks the health and lives of older adults across 29 European countries. They focused on a specific group of more than 40,000 people aged 65 and older who did not have dementia when the study began. The team followed these individuals over several years, checking in on them repeatedly to see who developed signs of probable dementia. To identify dementia, they used a method that combines memory tests—asking participants to recall lists of words—with questions about daily living skills, such as managing finances or preparing meals. By comparing the health histories of those who developed dementia against those who did not, the researchers could pinpoint which risk factors were most strongly linked to the disease in four distinct European regions: Northern, Western, Southern, and Central/Eastern Europe.

The study revealed that while some risks are universal, others are deeply local. Two factors stood out as consistent threats across the entire continent: depression and physical inactivity. In every region studied, people who were depressed or who did not engage in daily physical activity faced a significantly higher chance of developing dementia. This suggests that mental health and movement are fundamental pillars of brain protection, regardless of where one lives. However, the importance of other factors shifted dramatically depending on the region. For instance, low levels of education were a major driver of dementia risk in Southern and Central/Eastern Europe, where older generations often had fewer years of schooling. In contrast, this link was much weaker or non-existent in Northern Europe, where educational opportunities have historically been more widespread. Similarly, diabetes was a significant risk factor in Western, Southern, and Central/Eastern Europe, but it did not show a clear connection to dementia in the North.

When the researchers calculated how many dementia cases could theoretically be prevented if these risk factors were eliminated, the results highlighted even starker contrasts. The potential for prevention was highest in Southern Europe, where nearly half of all dementia cases might be linked to these modifiable risks. This high number was largely driven by the prevalence of low education in that region. In Central and Eastern Europe and Western Europe, the potential for prevention was also substantial, hovering around 40 percent. Northern Europe, however, showed a much lower figure, with only about a quarter of dementia cases potentially attributable to these factors. This does not mean dementia is less of a problem in the North, but rather that the specific risks the study measured—like low education or diabetes—play a smaller role there compared to other regions.

The study also uncovered unique regional patterns that would be missed by looking at Europe as a single block. In Western Europe, hearing loss, vision problems, smoking, and social isolation were all linked to higher dementia rates. In Southern Europe, obesity and vision loss emerged as specific concerns, adding to the burden of low education. In Northern Europe, where education levels are generally high and physical activity is common, social isolation stood out as a distinct risk factor, suggesting that even in well-resourced societies, being cut off from human connection can harm the aging brain. Interestingly, conditions often assumed to be major drivers, such as high blood pressure and high cholesterol, did not show a consistent link to dementia across any of the regions when all other factors were considered together. This suggests that while these conditions are dangerous for the heart, their direct relationship with dementia might be more complex or overshadowed by other lifestyle factors.

These findings point toward a clear conclusion: there is no single "one-size-fits-all" strategy for preventing dementia across Europe. While promoting physical activity and treating depression should be priorities everywhere, other efforts must be tailored to local realities. In Southern and Central/Eastern Europe, addressing educational gaps and managing diabetes could yield massive public health benefits. In the North, combating loneliness may be just as critical as managing physical health. The researchers emphasize that their work is based on observational data, meaning they found associations rather than proving direct cause-and-effect, but the consistency of the results across such a large population makes the patterns hard to ignore. By recognizing that the risks facing an older adult in Portugal differ from those facing someone in Sweden, policymakers can design targeted interventions that address the specific vulnerabilities of each community, offering a more hopeful path toward reducing the global burden of dementia.