A major international study analyzing data from over half a million participants in the United Kingdom and the United States has identified several modifiable risk factors linked to early-onset dementia, offering new insights for prevention strategies.

The research pooled and harmonised data from five large, long-term cohort studies, including the UK Biobank and the Framingham Heart Study, tracking 544,442 individuals over a median follow-up period of nearly 14 years.

During this time, researchers recorded 807 cases of early-onset dementia—defined as occurring before age 65—and more than 14,000 cases of late-onset dementia.

Stronger Links Found in Early-Onset Cases

The findings revealed that several health and lifestyle factors were more strongly associated with early-onset dementia than with cases that develop later in life.

Men were found to have a higher risk than women, with female participants showing a 30% lower likelihood of developing early-onset dementia. Racial disparities were also evident, with Black participants facing a significantly higher risk compared to White participants.

Among the most significant modifiable risk factors identified were diabetes and depression, both of which more than doubled the risk of early-onset dementia. Smoking also emerged as a major contributor, increasing risk by nearly 90%.

Other contributing factors included obesity, physical inactivity and excessive alcohol consumption. Lower levels of education were also strongly linked to increased risk, highlighting the role of social determinants in cognitive health.

While conditions such as hypertension and high cholesterol showed a trend toward increased risk, their associations were not statistically significant in this analysis.

Implications for Prevention

Researchers say the findings underscore the importance of targeting modifiable risk factors early in life to reduce the burden of dementia.

Unlike late-onset dementia, which is more commonly associated with aging, early-onset cases may be more influenced by lifestyle and environmental factors—making prevention strategies particularly impactful.

A Growing Public Health Concern

Dementia continues to pose a major global health challenge. Recent estimates suggest that in the United States alone, the lifetime risk of developing dementia after age 55 could be as high as 42%—a figure significantly higher than previously thought.

With projections indicating that annual new cases could reach one million by 2060, experts stress the urgency of early intervention.

The study’s authors conclude that addressing risk factors such as mental health, metabolic conditions and lifestyle behaviours could play a crucial role in reducing the incidence of early-onset dementia and improving long-term brain health.