New EdSHARe Research Counters the Claim that Fluoride Lowers IQ
New EdSHARe Research Counters the Claim that Fluoride Lowers IQ
News Release 19-Nov-2025
A new study, led by the EdSHARe research team and published in Science Advances, finds that fluoride is associated with better—not worse—cognitive performance in adolescence.
Using data from High School and Beyond (HS&B:80), a nationally representative cohort study of U.S. students followed from adolescence into late adulthood, the research is the first to investigate how exposure to government-recommended levels of fluoride in community water supplies affects cognitive performance in both secondary school and later adulthood.
Key Findings
- Children exposed to recommended levels of fluoride in drinking water through late adolescence do better than other children on vocabulary, reading, and mathematics achievement tests in 12th grade.
- This advantage persists, though it is no longer statistically significant, through approximately age 60.
- The study found no evidence of harm to cognition in adulthood among those exposed to typical fluoride levels in childhood.
- Analyses accounted for important confounding factors such as socioeconomic background, race and ethnicity, geographic region, and urbanicity.
Context
Fluoride is a naturally occurring mineral and is often added by municipalities to drinking water as a public health measure to strengthen teeth and reduce the risk of cavities. The U.S. Centers of Disease Control (CDC) cites fluoridation of drinking water as one of the top ten public health interventions of the 20th century, but misinformation has led some to worry that it harms children’s IQ. Previous studies raising concerns about negative effects of fluoride exposure on childhood IQ focused on extremely high levels not seen in U.S. water supplies. This new research addresses exposures within ranges most relevant to current American municipal water fluoridation policies.
Implications
- The findings support the safety and cognitive benefits of recommended fluoride levels in U.S. community water, adding to well-established oral health advantages.
- These results suggest that municipal water fluoridation, as practiced in the United States, is beneficial for adolescent cognition and poses no cognitive risks in later life.
Citation
Warren, John R., Gina Rumore, Soobin Kim, Eric Grodsky, Chandra Muller, Jennifer J. Manly, and Adam M. Brickman. 2025. "Childhood Fluoride Exposure and Cognition across the Life Course." Science Advances. 11(47). https://doi.org/10.1126/sciadv.adz0757.
New EdSHARe Study Compares Alzheimer’s Blood Biomarkers Across Racial and Ethnic Groups in Middle Age
News Release 21-Nov-2025
Using data from High School and Beyond (HS&B:80), a nationally representative U.S. cohort, the EdSHARe team found that blood-based Alzheimer’s disease (AD) biomarkers do not differ meaningfully across Black, Latinx, and White middle-aged adults.
The findings, published on JAMA Network Open, underscore the importance of representative sampling and accounting for common medical conditions when interpreting AD blood tests.
Key Findings
- After models were adjusted for population representativeness, average plasma concentrations of key AD biomarkers — Aβ42/Aβ40 (amyloid‑β ratio), pTau‑181 (phosphorylated tau‑181), NfL (neurofilament light chain), and GFAP (glial fibrillary acidic protein) — were statistically indistinguishable across race and ethnicity groups.
- Common medical conditions, like type 2 diabetes, Body Mass Index (BMI), and high cholesterol, were associated with biomarker levels similarly across all groups.
Context
Clinical AD incidence and prevalence are higher among Black and Latinx older adults than among White adults, yet prior studies comparing AD blood biomarkers by race and ethnicity have produced inconsistent results — often due to clinic-based or convenience samples that do not represent the broader population.
Implications
- Diagnostic and research use of AD blood biomarkers should prioritize population‑representative sampling and careful adjustment for comorbid conditions. The results do not support applying race‑specific diagnostic thresholds to biomarker concentrations in middle age.
- Health systems and clinicians implementing blood‑based AD tests should consider the influence of common conditions (e.g., diabetes, BMI, cholesterol) on biomarker values irrespective of race and ethnicity, to enhance precision and equity in early detection and monitoring.
Citation
Brickman, Adam M., Chandra Muller, John Robert Warren, Eric Grodsky, Soobin Kim, Michael J. Culbertson, Bharat Thyagarajan, Jennifer J. Manly. 2025. "Alzheimer Disease Blood Biomarker Concentrations Across Race and Ethnicity Groups in Middle‑Aged Adults." JAMA Network Open. 8(11):e2545046. https://doi.org/10.1001/jamanetworkopen.2025.45046.
According to a new HS&B:80 study, high school contexts - not just degrees - shape midlife cognitive functioning
News Release 26-Feb-2025
Using the nationally representative High School and Beyond (HS&B:80) cohort, EdSHARe research shows that midlife cognitive functioning is shaped not only by the degrees people earn but—importantly—by the academic performance and learning opportunities they experienced in high school.
The study, published on Alzheimer's & Dementia, finds that school contexts influence cognition primarily through their effects on students’ grades and test scores, indicating that prior research likely overstated the role of degree attainment alone.
Key Findings
- Degree attainment is associated with higher midlife cognitive functioning, but a substantial portion of that association is explained by students’ high school academic performance (grades, test scores, course completion).
- High school contexts and learning opportunities (e.g., school resources, curricular offerings, academic press) predict midlife cognition mainly because they shape students’ academic performance.
- Inequalities in educational opportunities and student performance—rooted in factors like race, class, and place—continue to matter for cognitive functioning even among people who ultimately achieve the same degrees.
Context
Decades of research link education to midlife and later-life cognitive functioning, but most studies operationalize education narrowly as “years of schooling” or “highest degree,” a coarse measure that can mask the diverse processes shaping cognition.
Scholarship on schooling environments documents large inequalities in resources, course rigor, and academic climate by race, class, and geography, yet cognitive-health studies frequently rely on proxy, state-level indicators that miss within-school variation and the learning opportunities students actually experience.
Implications
- Education policy and practice aimed at improving later-life cognitive health should focus upstream on equitable school resources, rigorous coursework, and support for high academic performance in high school—not only on degree completion.
- For accurate risk stratification and intervention design, Alzheimer's research and public health should conceptualize “education” beyond years or highest degree, incorporating exposures to school contexts, learning opportunities, and student performance that begin well before graduation.
Citation
Muller Chandra, Eric Grodsky, Adam M. Brickman, Jennifer J. Manly, Koit Hung, Michael J. Culbertson, John Robert Warren. 2025. "Education and midlife cognitive functioning: Evidence from the High School and Beyond cohort." Alzheimer’s & Dementia. 21:e70015. doi:10.1002/alz.70015.
Check out other publications from the EdSHARe research team!