A team of Cincinnati researchers is trying to tease out how lead poisoning affects the brain, and how these physical effects might correlate to behavioral changes. Living on Earth's Cynthia Graber reports.
CURWOOD: In the past few decades, researchers discovered that even tiny amounts of lead can be harmful to children, affecting such things as learn ability and impulse control. Lead is even linked to crime and juvenile delinquency. Researchers continue to unravel how early exposure to lead can have lifelong harmful effects. Leading this effort is a team of scientists in Cincinnati that's followed a group of lead-exposed children for two decades. Now, they're attempting to see just how lead affects brain structure. Living on Earth’s Cynthia Graber has this latest installment in our series, “The Secret Life of Lead.”
TURNER: Is your pizza pretty good?
GRABER: Nikki Turner is this new study’s project coordinator. She’s with 21-year-old Lamont in the cafeteria at Cincinnati Children’s Hospital, giving him a free lunch before his MRI exam.
LAMONT: I’m not really hungry because I want to get the MRI out of the way first. I’m a little nervous about this.
GRABER: Twenty years ago, the University of Cincinnati, along with Cincinnati Children’s Hospital, began a long-term study to learn about lead exposure. Lamont is one of almost 200 young adults who have been with the study since birth. Back then, lead poisoning was considered a serious problem only when it produced physical effects such as seizures. Lamont, along with most others in the group, most likely had childhood blood lead levels that at the time were considered safe, but that today might be cause for concern. Research on this group demonstrated that these lower levels can cause a variety of developmental problems, including difficulties with learning, attention, and planning ahead.
[MACHINE CHIRPING, TECHNICIAN TALKING]
GRABER: Inside the MRI room, a pump chirps as it circulates helium that keeps the MRI cool. Technician Scott Dunn settles Lamont in.
DUNN: The table goes up and you pull the bucket over your head.
GRABER: Lamont lies down on a long table. His head is strapped firmly in place, and what looks like a plastic bucket is placed over it. Once he’s secure and comfortable, he slides head-first into the beige scanner.
[SOUND OF DOOR CLOSING]
GRABER: Dunn returns to the control room and sits down at the computer.
DUNN: Okay, here we go.
[CLICKING OF COMPUTER]
GRABER: Photos of Lamont’s brain soon appear on the computer screen. Kim Cecil, a chemist with Cincinnati Children’s Hospital, sits in the control room and looks on. Cecil specializes in MRI research and is the lead scientist on this study. She says this new research is crucial because there is very little information connecting lead’s impact on development to what physically happens to a lead-exposed brain.
CECIL: So there’s really a void between the basic cellular work and the behavioral work. No one’s really gone in and looked at the brain in vivo to see what’s going on.
GRABER: Cecil hopes this MRI study will change that.
CECIL: Magnetic resonance imaging can provide structural information, anatomical information. Are the ventricles too big or too small? Is the grey matter where it’s supposed to be? Is it formed correctly?
GRABER: Another part of the study involves magnetic resonance spectroscopy, a process that measures the amounts of chemicals in specific regions of the brain. Based on that information, scientists can tell how well those parts of the brain are functioning. A final test involves what’s called functional imaging, looking at how the brain works while it’s working. Researchers are focusing on activities lead is known to affect, such as concentration.
CECIL: What we do in this study is that we designed tasks that involved language, working memory and attention. So, we do these neuropsychological tests within the MRI scanner. And while the subject is doing these tests, we monitor where that blood flow is going.
GRABER: This research is based on an earlier study Cecil worked on comparing the brains of 16 lead-exposed children to those of their unaffected relatives.
CECIL: We found that in the frontal grey matter, the children with lead exposure had lower n-acetyl-aspartate levels, which is the neuronal marker.
GRABER: That means their brain formation may have been altered by lead which may or may not correlate to behavioral effects. Those links haven’t been studied yet. In this study, Cecil has already examined the brains of about 50 young adults. She says to her naked eye, the brain structure and chemicals look okay compared.
CECIL: It’s not striking. There’s not out of the ballpark abnormal. And so it’s going to require rigorous analysis to figure it out.
GRABER: That’s because her eye can’t detect, say, a ten percent difference in one chemical or another, a difference that could be significant.
Neuropsychologist Douglas Ris is one of Cecil’s colleagues. He heads up another part of the Cincinnati lead research, examining the link between childhood lead exposure and adult anti-social behavior. And he’s using the same group of young adults. Ris hopes that Cecil’s evidence will link physical changes in the brain to the results of his behavioral research. That’ll be a challenge, though, he says, because it’s difficult to pinpoint exactly where in the brain researchers should look.
RIS: There is no center for criminality or delinquency or conduct problems. Rather, when we talk about these complex behaviors and what causes them and what parts of the brain mediate them, we usually talk about multiple areas of the brain that work in concert to influence behaviors and development.
GRABER: So the MRI team has chosen to focus on regions of the brain that may control things like inhibitions and the regulation of emotion – factors that are thought to play a role in criminal behavior. But even if these regions are found to have been modified in some way from lead exposure, it still will not be simple to show a direct cause and effect.
RIS: It’s unlikely to me that it’s going to be a very straightforward kind of relationship. Nothing in this area is. We also have to take into account the series of factors that go into producing anti-social behavior and things in adolescents and adults.
GRABER: These include family income, nutrition, and the level of maternal education.
[BUZZING FROM MRI]
DUNN: And that’s the end of this dance. Lamont have you had enough? Are you still in there?
LAMONT: Uh huh.
DUNN: Okay. Coming to get you out, okay?
GRABER: Technician Scott Dunn walks into the MRI room and helps Lamont out of the scanner. They return to the control room so Lamont can check out his brain.
DUNN: So that’s that. This is your brain.
LAMONT: So everything is normal?
LAMONT: Oh, okay. I didn’t know it would look like this. [LAUGHTER]
GRABER: Researchers hope that Lamont’s brain and the almost 200 others in the study will not only provide a greater understand of how lead does its damage, but also help provide clues for treating lead poisoned children. For Living on Earth, I’m Cynthia Graber.
[MUSIC: Sparta “Cataract” WIRETAP SCARS (Dreamworks – 2002)]
CURWOOD: For more on lead and lead research, go to our website, livingonearth.org. You’ll find an in-depth look at cutting-edge science on the connection between childhood lead exposure and criminal behavior later in life. Explore “The Secret Life of Lead” on our website, livingonearth.org.
[MUSIC: Sparta “Cataract” WIRETAP SCARS (Dreamworks – 2002)]
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