Lead exposure before birth is linked to lower cognitive scores 60 years later

The teeth children lose naturally in early childhood carry a chemical record of what their bodies were exposed to before birth. A study published February 18, 2026 in Neurology, the journal of the American Academy of Neurology, retrieved that record from donated baby teeth collected decades ago and used it to ask whether lead exposure before birth is associated with how well people think and remember in their sixties and beyond.

The answer, particularly for women, is that it is. The study does not establish causation - it identifies an association - but the association is specific, quantifiable, and robust to the analytical approaches the researchers used.

How the study worked: teeth as time capsules

Lead exposure leaves measurable deposits in developing teeth during fetal life and early childhood. Baby teeth shed in middle childhood can be analyzed for lead content layered into the dentine during specific developmental windows. The researchers used teeth donated in the 1960s and 1970s as part of earlier scientific programs, when lead exposure in the United States was at or near its peak - leaded gasoline, lead paint, and lead-containing plumbing were all common. Children born during that era are now in their sixties, and cognitive testing data for some of those individuals allowed the research team to connect early-life exposure to later-life function.

The analysis focused specifically on lead concentrations in the dentine laid down during the second trimester of pregnancy, which represents a distinct developmental window. Cognitive tests administered approximately 60 years after birth assessed thinking and memory skills.

The association and its magnitude

Higher second-trimester lead levels in teeth were associated with lower scores on cognitive tests in older adulthood. The relationship was primarily found among female participants. The magnitude is clinically interpretable: each increase of one part per million in second-trimester tooth lead concentration corresponded to cognitive test performance equivalent to approximately three additional years of aging in women.

That framing - translating the association into years of cognitive aging - gives the finding practical intuition. Three years of cognitive aging represents a meaningful difference in an older adult's daily function and long-term dementia risk trajectory, even if it does not by itself indicate clinical impairment.

Why women and not men?

The sex-specific pattern - associations found primarily in women - is one of the study's most intriguing and least explained findings. Several biological mechanisms could theoretically account for sex differences in how prenatal lead affects long-term cognition: sex hormones influence both lead distribution in bone and cognitive reserve accumulation; women's longer life expectancy means they survive into age ranges where cognitive changes are more detectable; and lifetime exposure patterns differ by sex. The study does not adjudicate between these explanations, and the authors do not claim to know why the sex difference exists. Replication in other cohorts with sex-stratified analyses is needed.

Limitations and what this study cannot tell us

The association between prenatal lead and later cognition is statistically present after adjustment for confounders, but tooth-based lead measurement captures lead exposure during specific windows, not total lifetime exposure. Adults who had high prenatal lead exposure in the 1960s also grew up in an era of high childhood and adult lead exposure - from paint, gasoline, and water pipes - making it difficult to isolate the prenatal period's specific contribution.

The sample was drawn from individuals who had donated baby teeth decades ago and who could be located and cognitively tested in later life, which is not a random sample of the population. Individuals with severe cognitive impairment would be harder to include, potentially underestimating the true association. The study is also observational: it cannot rule out that some unmeasured variable explains both higher prenatal lead and lower cognitive scores later in life.

The findings are nonetheless meaningful for understanding the long reach of environmental exposures. Lead exposure in the United States peaked during the 1960s through 1980s. The cohort of people born then is now entering midlife and older adulthood. If prenatal lead exposure contributed to their cognitive trajectories, the public health consequences are distributed across millions of individuals - many of whom have never had their early-life exposure measured.