The Impact of Childhood Cognitively Stimulating Activities on the Association between Prenatal and Early Postnatal Lead Exposure and Later Adulthood Cognitive Function

Abstract

Abstract Introduction: Early lead exposure is linked to cognitive function in later adulthood. In animal studies, enriched environments appear to protect against adverse effects of lead exposure, but there has been limited exploration in humans. Our objective was to assess whether engagement in cognitively stimulating activities in childhood modifies the association between early lead exposure and later adult cognitive function. Methods: Participants come from the St. Louis Baby Tooth – Later Life Health Study (SLBT), a cohort study which recruited beginning in 2021. SLBT is composed of individuals primarily from the St. Louis, USA area who donated deciduous (baby) teeth to a prior study, the Baby Tooth Survey, in 1958–1972. Participants who completed a survey and cognitive testing were selected through stratified random sampling for tooth lead analysis. Prenatal and postnatal tooth dentin lead concentrations were measured in the donated teeth using laser ablation inductively coupled plasma mass spectrometry. A summary cognitive function score was derived from z-scored outcomes on six cognitive tests completed online through the TestMyBrain platform. Participation in cognitively stimulating activities at ages 6, 12, and 18 years was retrospectively assessed at the time of cognitive testing with the Rush Alzheimer’s Disease Center Lifetime Cognitive Activities scale. Results: From 4236 participants who completed the survey and cognitive tests, 717 had tooth metals analyzed, from which 704 had non-outlying lead measures and sufficient survey information. Participants were on average 62 years (SD = 3.6) at the time of cognitive testing, and 376 (53%) were female. The level of cognitively stimulating activities averaged across childhood modified the effect of second-trimester lead exposure on later adulthood cognitive function. For those with less-frequent childhood cognitively stimulating activities, 1 ppm higher second-trimester lead was associated with 0.34 (95% CI: −0.52, −0.16) SD lower later adulthood cognitive function, while the association among those with high cognitively stimulating activities was null (−0.02 SD, 95% CI: −0.12, 0.07). Results were robust to adjustment for additional childhood socioeconomic characteristics and restriction to white non-Hispanic race. Conclusions: Our work supports the hypothesis that engaging in cognitively stimulating activities in childhood, after earlier lead exposure, could buffer its deleterious effects on later adult cognitive function.