Risk of lead exposure linked to decreased brain volume in adolescents
January 13, 2020
Science Daily/Children's Hospital Los Angeles
In a study using brain scans from nearly 10 thousand adolescents across the country, investigators show that risk of lead exposure is associated with altered brain anatomy and cognitive deficits in children from low income families.
Though leaded gas and lead-based paint were banned decades ago, the risk of lead exposure is far from gone. A new study led by Elizabeth Sowell, PhD, shows that living in neighborhoods with high risk of lead exposure is associated with differences in brain structure and cognitive performance in some children. Her findings, published by Nature Medicine, also show a deeper trend -- children in lower income families may be at increased risk.
Dr. Sowell and her team at The Saban Research Institute of Children's Hospital Los Angeles hypothesized that children in lower income families could be particularly vulnerable to the effects of living in high lead-risk environments. Their previous findings show that the socioeconomic status of families affects brain development. Here, they examined the association of lead exposure risk with cognitive scores and brain structure in more than 9,500 children.
Dr. Sowell's laboratory is part of the Adolescent Brain Cognitive Development (ABCD) Study, which has enrolled nearly 12,000 children from 21 sites across the United States. ABCD follows participants from the age of 9-10 into adulthood, collecting health and brain development information. It is the largest and most comprehensive study of its kind. The wealth of data collected through ABCD allows investigators like Dr. Sowell to ask questions about factors that affect adolescent brains.
Their results showed that an increased risk of lead exposure was associated with decreases in cognitive performance and in the surface area and volume of the cortex -- the surface of the brain, responsible for initiating conscious thought and action. But this was not true for children from mid- or high-income families.
No amount of lead is safe. Even at very low levels, cognitive deficits have been attributed to lead exposure. More than 72,000 neighborhoods in the United States have been assigned risk estimates for lead exposure, based on the age of homes and poverty rates. Though new houses haven't used lead-based paint since 1978, many older homes still contain lead hazards.
"Professional lead remediation of a home can cost $10,000," says Dr. Sowell, who is also a Professor of Pediatrics at the Keck School of Medicine of USC. "So, family income becomes a factor in lead exposure." Indeed, as her study reveals, the associations between lead risk and decreases in cognitive performance and brain structure are more pronounced in lower income families.
"We were interested in how lead exposure influences brain anatomy and function," says Andrew Marshall, PhD, a postdoctoral research fellow in Dr. Sowell's lab and first author of the publication. "Cognition is affected by low-level lead exposure, but there weren't any published studies about brain structure in these children."
Decreased cognitive scores and structural brain differences were only observed in lower-income families. "What we're seeing here," says Dr. Marshall, "is that there are more pronounced relationships between brain structure and cognition when individuals are exposed to challenges like low income or risk of lead exposure." The ABCD study has not yet examined blood lead levels in these children, but the authors of this publication showed that risk of lead exposure is predictive of blood lead levels. Further studies are needed to determine the precise cause for these differences, such as whether lead exposure itself or other factors associated with living in a high lead-risk environment is contributing to this association, but the study unveils a clear correlation between family income and the effects of living in high lead-risk census tracts.
However, Dr. Sowell emphasizes that income and risk of lead exposure do not define a child. "It's absolutely not a foregone conclusion that these risks make you less intellectually capable," she says. "Many children who live in low-income, high-risk areas will be successful." Her goal is to promote awareness of how environmental toxins affect children. Understanding what our children face is the first step in helping them.
"Even though lead levels are reduced from three decades ago in the environment, it's still a highly significant public health issue," says Dr. Sowell. Despite this, there are kids in high-risk environments that do not show these deficits, indicating that it is possible to mitigate lead effects.
"The take home point is that this can be fixed," she says. "Lead does not have to be in the environment. We can remove it and really help kids get healthier."
https://www.sciencedaily.com/releases/2020/01/200113111155.htm
Lead exposure impacts children's sleep
Novel finding shows that lead exposure in early childhood increase risk for sleep problems, excessive daytime sleepiness
November 12, 2015
Science Daily/University of Pennsylvania School of Nursing
Lead exposure in early childhood are associated with increased risk for sleep problems and excessive daytime sleepiness in later childhood, new research shows. This is the first longitudinal, population-based study that investigated early lead exposure to sleep problems.
The research is based on data from a longitudinal, cohort study -- involving more than 1400 Chinese children -- that began in 2004 investigating the influence of lead exposure in relation to the development of children and adolescents' neurocognitive, behavioral and health outcomes. Lead pollution is pervasive throughout China and other developing countries, and though rates of lead exposure are decreasing due to the phase-out of leaded gasoline and increased public awareness, its persistence presents a significant health risk to children.
"Little is known about the impact of heavy metals exposure on children's sleep, but the study's findings highlight that environmental toxins -- such as lead -- are important pediatric risk factors for sleep disturbance," said the study's principal investigator Jianghong Liu, PhD, FAAN, Associate Professor at Penn Nursing and a faculty member at Penn's Perelman School of Medicine. "Lead exposure is preventable and treatable, but if left unchecked can result in irreversible neurological damage."
This is an important advancement in identifying and understanding the contribution of lead exposure to childhood insomnia and daytime sleepiness. Sleep problems are highly prevalent in children and adolescents and are associated with many adverse health outcomes including developmental disorders and intellectual and neurocognitive problems.
"This study addresses an important but often neglected area of sleep science, namely, environmental factors that disrupt sleep biology and behavior in children and other vulnerable populations," said the study's senior author David Dinges, PhD, Professor and Chief of the Division of Sleep & Chronobiology in the Department of Psychiatry at Penn Medicine.
The sleep problems reported by the adolescents in the study include excessive daytime sleepiness, insomnia, early morning awakening, trouble initiating and maintaining sleep, and having to use sleeping pills, all of which highlight poor sleep quality. Using the data from the cohort study, 665 children's blood lead levels were assessed when they were between three and five years old, and sleep was assessed six years later, when the children were between nine and eleven years old. The children and their parents answered separate questionnaires about the children's daily sleep patterns, insomnia and the use of sleeping pills.
Child-reported insomnia and use of sleeping pills were two times and three times more prevalent in children with blood lead levels (BLL) greater than or equal to 10 ug/dL than in children with BLL less than 10 ug/dL. This suggests that sleep disturbances appeared problematic enough for children to suffer from insomnia and even to use sleeping aids/pills in an attempt to ameliorate their symptoms.
"Insufficient sleep and daytime sleepiness is very prevalent in children and adolescents, and it is a pervasive problem that is linked with a significant public health burden," explained Liu. "More research needs to be done to identify contributing factors and ways to prevent or reduce their impact. Doing this can not only help alleviate sleep disturbance, but can also indirectly improve sleep-related health outcomes, including cognition, emotion, behavior, and in some cases, diabetes."
http://www.sciencedaily.com/releases/2015/11/151112161427.htm