Three new NIEHS-funded studies underscore links between exposures that a child experiences in the womb and effects on health and well-being in later life.
The first study, from Columbia University, linked air pollution and material hardship with increased attention deficit hyperactivity disorder (ADHD). In the second, researchers at Drexel University found that prenatal supplements may lower the prevalence of autism accompanied by intellectual disability. The third paper reported a potential tool for reversing certain effects of prenatal lead exposure.
Air pollution plus economic hardship worsens ADHD
High prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) combined with material hardship is associated with increased symptoms of ADHD at age 9 years, according to a first-of-its-kind study by NIEHS-funded researchers at Columbia University.
PAHs are carcinogenic and neurotoxic by-products of combustion commonly found in urban air. Exposure to PAH is disproportionately high in low-income communities, which also experience long-term economic stress.
Between 1998 and 2006, the researchers enrolled nonsmoking, pregnant African-American and Dominican women in New York City and followed their children through 9 years of age. Among the 351 children in the study sample, co-exposure to socioeconomic disadvantage and air pollution in early life significantly increased ADHD behavior problems.
“The study provides continued support and evidence that environmental factors are neurotoxicants and that the effects are mediated by maternal hardship,” said Kimberly Gray, Ph.D., NIEHS health scientist administrator. “The combined effects may help elucidate specific mechanisms that may help guide future interventions.”
Multivitamins in pregnancy may lower risk of ASD with intellectual disability
Maternal multivitamin supplementation during pregnancy is associated with a lower incidence of autism spectrum disorder (ASD) with intellectual disability in children, according to a NIEHS-funded study conducted by researchers at Drexel University.
The research team wanted to learn more about inconsistent results in studies of whether maternal use of multivitamins, iron, or folic acid protects children against ASD. They identified 273,107 mother-child pairs through population registers in Sweden and assessed multivitamin, iron, and folic acid supplement use.
The study reported that prevalence of ASD with intellectual disability was 0.26 percent among children whose mothers reported taking multivitamin supplements compared with 0.48 percent among children whose mothers did not use multivitamins.
“Whether the association is specific to autism or reflects the risk of intellectual disability needs to be explored in future research,” the authors noted. “Given the current understanding and strength of evidence supporting the importance of nutritional supplementation during pregnancy, these results on their own should not change current practice.”
Promise for treating lead-induced neuronal dysfunction
A small molecule found in a variety of plant species reverses certain effects of long-term lead exposure in rats, according to NIEHS-funded research at Florida International University (FIU).
Lead exposure during development is thought to produce learning deficits by disrupting signaling between neurons in a brain region called the hippocampus. Specifically, lead exposure reduces cellular communication by interfering with the ability of hippocampal neurons to release vesicles containing signaling chemicals called neurotransmitters.
In this study, researchers demonstrated, for the first time in an animal model, that a small molecule called 7,8-dihydroxyflavone (7,8-DHF) reverses the long-term effects of lead exposure on vesicle release from hippocampal neurons. 7,8-DHF is naturally present in certain tree leaves and flowering plants.
Daily treatment with 7,8-DHF completely reversed lead-induced impairments in vesicle release in rats that were exposed to lead both prenatally and postnatally. “Although the findings suggest that 7,8-DHF might be a safe and effective intervention for lead-exposed children, future studies are needed to determine whether this pharmacological approach leads to a permanent reversal of lead-induced learning deficits,” said Jonathan Hollander, Ph.D., NIEHS health scientist administrator.
Perera FP, Wheelock K, Wang Y, Tang D, Margolis AE, Badia G, Cowell W, Miller RL, Rauh V, Wang S, Herbstman JB. 2017. Combined effects of prenatal exposure to polycyclic aromatic hydrocarbons and material hardship on child ADHD behavior problems. Environ Res pii: S0013-9351(17)31225-2.
DeVilbiss EA, Magnusson C, Gardner RM, Rai D, Newschaffer CJ, Lyall K, Dalman C, Lee BK. 2017. Antenatal nutritional supplementation and autism spectrum disorders in the Stockholm youth cohort: population based cohort study. BMJ 359:j4273.
Zhang XL, McGlothan JL, Miry O, Stansfield KH, Loth MK, Stanton PK, Guilarte TR. 2017. 7,8-dihydroxyflavone rescues lead-induced impairment of vesicular release: a novel therapeutic approach for lead intoxicated children. Toxicol Sci; doi:10.1093/toxsci/kfx210 [Online 4 October 2017].
(Janelle Weaver, Ph.D., is a contract writer for the NIEHS Office of Communications and Public Liaison.)