The Impact of Early Life on Dementia Risk

Recent discussions on dementia prevention have focused heavily on lifestyle changes—exercise, diet, and education—as solutions to delay or avoid the disease. The Lancet Commission identified 14 modifiable risk factors, including smoking, physical inactivity, and low education levels, claiming that nearly half of dementia cases could potentially be prevented or delayed. While this is encouraging, a growing body of research suggests that the roots of dementia may lie much earlier in life, raising critical questions about how we approach prevention.

The Importance of Early-Life Factors

Professor Anders Martin Fjell, a leading researcher in brain development at the University of Oslo, argues that early-life factors often have a far greater impact on dementia risk than mid-life or late-life choices. Fjell’s research, based on thousands of MRI scans from participants aged 0 to 100, reveals that many differences in brain health observed in older adults can be traced back to conditions and influences from childhood—or even earlier in the womb.

One key factor highlighted is birth weight, which acts as a marker for prenatal conditions. Lower birth weight, often an indicator of unfavorable conditions in utero, correlates with smaller brain structures and a higher risk of dementia. Even among identical twins, the twin with the higher birth weight often has a larger brain area and a lower risk of dementia, suggesting that prenatal environment—not just genetics—plays a crucial role.

Similarly, long-term studies in Scotland have demonstrated that cognitive abilities measured as early as age 11 strongly predict cognitive performance in old age. Fjell notes that much of the variation in cognitive function among older adults is rooted in differences present from a young age, rather than mid-life behaviors. This challenges the notion that dementia can be fully addressed through changes later in life.

Questioning Lifestyle and Education as Solutions

While the Lancet Commission’s risk factors, such as physical inactivity and education, are correlated with dementia, Fjell urges caution in interpreting these links as causal. For example, while education is associated with lower dementia rates, Fjell’s research suggests this may reflect a selection bias—those with higher cognitive abilities are more likely to pursue higher education, rather than education itself protecting against dementia.

This criticism extends to other factors like exercise. Observational studies often show strong correlations, but randomized controlled trials, considered the gold standard in research, fail to confirm that exercise directly reduces dementia risk. Instead, Fjell emphasizes that physical activity benefits overall health, improving heart, lung, and muscle function, which indirectly supports cognitive resilience but may not prevent dementia directly.

Shifting Focus to Early Interventions

The implication of Fjell’s findings is clear: to truly reduce dementia risk, interventions must begin early. Maternal and prenatal health, as well as early childhood development, play a pivotal role. Addressing issues like maternal nutrition, reducing exposure to harmful substances such as tobacco and alcohol, and improving access to quality prenatal care may have profound impacts on long-term cognitive health.

For instance, studies have shown that the prenatal environment directly affects birth weight and brain development, factors that set the stage for lifelong brain health. Early childhood education and cognitive enrichment may also enhance cognitive reserves, offering protection against age-related decline.

A Balanced Perspective for Patients

For individuals diagnosed with dementia, Fjell emphasizes that self-blame is unwarranted. He advises focusing on activities that bring joy and fulfillment, rather than adopting lifestyle changes out of fear of dementia. Engaging in hobbies, maintaining social connections, and staying physically active should be viewed as ways to enhance overall quality of life, rather than as guarantees against cognitive decline.

Moving Forward: A Broader Vision for Prevention

While the Lancet Commission’s list of modifiable risk factors offers actionable steps for many, Fjell’s research highlights the need for a more comprehensive approach. Public health efforts should prioritize early-life interventions, including improved prenatal care, childhood education, and addressing social inequalities. These foundational measures could have far-reaching benefits, not just for reducing dementia but for improving overall health outcomes across the lifespan.

In conclusion, while lifestyle changes remain valuable for general health, the evidence increasingly suggests that what happens before we are even born, and in our earliest years, has a profound influence on brain health in later life. A shift in focus toward these critical early periods may hold the key to more effective dementia prevention strategies.

References

1. Fjell, A. M., & Walhovd, K. B. (2024). Insights from MRI Studies on Brain Development and Cognitive Aging. University of Oslo Center for Lifespan Changes in Brain and Cognition.
2. Livingston, G., Huntley, J., Sommerlad, A., et al. (2020). Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. The Lancet, 396(10248), 413–446.
3. Jakobsen, S. E. (2024). “You can’t jog or eat your way to preventing dementia,” researcher says. forskning.no.
4. Strand, B. H. (2024). Perspectives on Longitudinal Dementia Research. Norwegian Institute of Public Health.
5. Scottish Council for Research in Education. (1998). The Scottish Mental Surveys of 1932 and 1947. Scottish Academic Press.