A study published on 18 February 2026 in Neurology suggests that exposure to lead before birth may be linked to reduced cognitive performance later in life. Researchers found that female participants who had higher levels of prenatal lead exposure tended to perform worse on tests that measured thinking and memory skills when they were around sixty years old. The authors of the study emphasised that their findings show an association rather than a direct cause-and-effect relationship. In other words, while prenatal lead exposure was related to lower test scores decades later, the research does not prove that lead exposure itself caused the decline in cognitive performance.
The research was led by Ruby C. Hickman, who conducted the study while working at the Harvard T.H. Chan School of Public Health. Hickman explained that lead exposure in the United States reached its highest levels during the 1960s, 1970s, and 1980s. Many people born during those decades are now entering middle age or older adulthood, a period when the long-term effects of early environmental exposures may become more noticeable. According to Hickman, examining how prenatal exposures influence cognitive health later in life is important for understanding the lasting impact of environmental hazards.
To estimate the participants’ early exposure to lead, researchers relied on an unusual and valuable source of biological evidence: baby teeth. Decades earlier, between 1958 and 1972, parents living in the St. Louis, Missouri area had donated their children’s baby teeth to a separate study that focused on radiation exposure. The teeth were carefully preserved, creating a unique historical record. Many years later, the research team worked to locate the individuals who had originally donated those teeth and invited them to participate in new testing designed to measure their cognitive abilities.
Baby teeth provide important information about environmental exposure because they absorb substances from the body as they form. As teeth develop, elements such as lead can become incorporated into their structure. By analysing the chemical composition of these teeth, scientists can estimate the level of lead that individuals were exposed to before birth and during early childhood. Using this approach allowed researchers to reconstruct prenatal exposure levels even though several decades had passed since the participants were born.
In total, the study included 715 participants who were successfully located and agreed to take part in the research. The average age of the participants was approximately sixty-two. Each participant completed a series of cognitive tests on their home computers or digital devices, allowing researchers to evaluate their thinking and memory skills. The baby teeth from these participants were also analysed for lead content. The median concentration of lead in the teeth was found to be 1.34 parts per million, providing a measure of the participants’ early exposure levels.
The results showed that among female participants, higher levels of prenatal lead exposure were associated with lower scores on cognitive tests later in life. Specifically, each increase of one part per million in lead concentration during the second trimester of pregnancy corresponded with test scores that were 0.16 standard deviations lower. In the researchers’ analysis, this difference was roughly equivalent to about three additional years of cognitive ageing. The researchers also noted that the study had limitations, including the fact that most participants were white and had relatively high educational and socioeconomic backgrounds during childhood, which means the findings may not apply equally to more diverse populations.
More information: Ruby C. Hickman et al, Prenatal and Early Postnatal Lead Exposure and Later Adulthood Cognitive Function in the St. Louis Baby Tooth–Later Life Health Study, Neurology. DOI: 10.1212/WNL.0000000000214616
Journal information: Neurology Provided by American Academy of Neurology
