Research notes: fluoride, firearms, and screen time

Is anyone interested in a few nibbles of research news she may have missed?

Here are three posts from JAMA Pediatrics, one of Earth’s leading journals about medical research about children. Although I didn’t consider any one of these important enough to merit a full post, I did want to pass them along to you, Dear Readers. They aren’t expressly about disabilities, but they’re about matters that some who are concerned about our kids might wonder about possible implications.

It’s valuable to keep up with what’s happening in allied disciplines, don’t you think.

Fluoride and IQ

Deleterious effects of some environmental toxins on IQ, especially lead, have prompted renewed apprehension about a long-standing question: Does exposure to fluoride decrease IQ? Taylor et al. (2025) systematically reviewed and meta-analysed the research on the question and found there is a correlation between fluoride exposure and IQ, with higher levels of exposure being associated with lower IQ (and vice versa). The correlations anot as strong when the researchers only considered studies that were less likely to be biased and with low levels of exposure (< 1.5 mg/L) in studies that were rated as less likely to be biased.

Parents and educators should understand that few children are exposed to levels of fluoride at high and the upper limit of the lowest levels Professor Taylor and colleagues found to have effects (1.5 mg/L); US and other health agencies recommend limiting exposure to < 0.7 mg/L. In addition, we need to understand that the decreases in IQ in this study were about 1 (one) IQ point.

Taylor, K. W., Eftim, S. E., Sibrizzi, C. A., Blain, R. B., Magnuson, K., Hartman, P. A., Rooney, A., & Bucher, J. R. (2025). Fluoride exposure and children’s IQ scores: a systematic review and meta-analysis. JAMA Pediatrics, 179(3), 282-292. https://doi.org/10.1001/jamapediatrics.2024.5542

Firearm mortality

More US children die by firearms than by any other single cause of death. We might worry about whether lax policies-laws in geopolitical entities might lead to greater mortality for children. Faust and colleagues (2025) assessed mortality rates in US states that enacted permissive firearm laws after the US Supreme Court ruled that state and local governments could not ban ownership of handguns. They examined the frequency of children dying before and after the 2010 ruling in states that had (a) the most permissive gun policies, (b) permissive policies, or (c) strict policies. They found about 159 excess firearm deaths per million population in the states with the most permissive policies, 108 in the states with permissive policies, and -55 excess firearm deaths in the states with the strictest policies. Said simply: States with the most permissive and permissive firearm laws had greater pediatric firearm mortality after the US Supreme Court decision.

Those of us who are concerned about our kids dying from firearms (whether by gang violence, mass shooting, suicide, or accident) might want to tuck these findings away for a future discussion of gun control.

Faust, J. S., Chen, J., Bhat, S., Otugo, O., Yaver, M., Renton, B., Chen, A. J., Lin, Z., & Krumholz, H. M. (2025). Firearm laws and pediatric mortality in the US. JAMA Pediatrics, 179(8). https://doi.org/10.1001/jamapediatrics.2025.1363

Adolescents’ screen time, brains, sleep, and depression

In contemporary society, people are concerned about the inflrunece of using mobile devises on the mental health of youths. Lima Santos and colleagues (2025) assessed the extent to which the correlation between screen time and youth depression was influenced by sleep time and organization in the white matter parts of the brain. Their study of nearly 1000 early adolescents at two time points showed that “more screen time in late childhood was associated with more depressive symptoms, potentially due to shorter sleep and worse white matter organization during early adolescence.”

This is only correlational evidence, so there’s no guarantee that promoting fewer minutes of screen time and more minutes of sleep, but these results should encourage us to test possible changes in pre- and early-adolescents’ behavior.

Such changes merit experimental evaluation.

Lima Santos, J. P., Soehner, A. M., Biernesser, C. L., Ladouceur, C. D., & Versace, A. (2025). Role of sleep and white matter in the link between screen time and depression in childhood and early adolescence. JAMA Pediatrics, 179(9). https://doi.org/10.1001/jamapediatrics.2025.1718