Skip to main content
Accessibility  |  About  |  Contact  |  Privacy  |  Terms

Lead May be the Culprit in ADHD

  • Published: 2010-01-28 : Association for Psychological Science.
  • Synopsis: New research suggests lead may be the cause of ADHD and explains the causal pathway from exposure to disability.

Main Document

ADHD, or attention-deficit/hyperactivity disorder, is among the costliest of behavioral disorders. Its combination of inattention, impulsivity and hyperactivity leads to accidental injuries, school failure, substance abuse, antisocial behavior and more. Yet despite nearly a century of study, the disorder's roots remain mysterious.

Much of modern ADHD research has focused on heritability of the condition, and indeed evidence suggests that genes may account for as much as 70 percent of hyperactivity and inattention in children. But that leaves 30 percent unexplained, so recently the focus has shifted to the environment. What is it that triggers an underlying susceptibility and changes it into a full-blown disorder? New research suggests that the culprit may be an old villain lead and what's more it explains the causal pathway from exposure to disability.

Lead is a neurotoxin. This has been known for a long time, and in fact government regulation drastically reduced environmental lead a generation ago. But regulating automobile fuel and paint didn't entirely eliminate lead from the environment. It's found in trace amounts in everything from children's costume jewelry to imported candies to soil and drinking water. Every American today is exposed to low levels of the metal, and indeed nearly all children have measurable levels of lead in their bodies. According to psychological scientist Joel Nigg of the Oregon Health & Science University, this universal low-level exposure makes lead an ideal candidate for the disorder's trigger.

This was just a theory until quite recently, but two recent studies now provide strong evidence. The first study compared children formally diagnosed with ADHD to controls, and found that the children with the disorder had slightly higher levels of lead in their blood. This study showed a link only between blood lead and hyperactivity/impulsivity symptoms, not inattention. But a second study showed a robust link between blood lead and both parent and teacher ratings of ADHD symptoms, including both hyperactivity and attention problems. In both studies, the connection was independent of IQ, family income, race, or maternal smoking during pregnancy.

Nigg offers a causal model for the disabling symptoms associated with ADHD: Lead attaches to sites in the brain's striatum and frontal cortex, where it acts on the genes in these regions causing them to turn on or remain inactive. Gene activity shapes the development and activity of these brain regions. By disrupting brain activity, the toxin in turn alters psychological processes supported by these neurons, notably cognitive control. Finally, diminished cognitive control contributes to hyperactivity and lack of vigilance. Nigg describes his new data and his explanatory model in the February issue of the journal Current Directions in Psychological Science .

Similar Topics

1 - What Can Twitter Reveal About People with ADHD - University of Pennsylvania.
2 - Can Adults Develop ADHD? - Florida International University.
3 - School Year Relative Age Causing Bias in ADHD Diagnosis - University of Nottingham.
4 - Is ADHD Associated with Lack of Regular Circadian Sleep - European College of Neuropsychopharmacology.
5 - Harnessing ADHD for Business Success Study - Technical University of Munich (TUM).
From our ADHD and ADD section - Full List (51 Items)

Submit disability news, coming events, as well as assistive technology product news and reviews.


Loan Information for low income singles, families, seniors and disabled. Includes home, vehicle and personal loans.


Famous People with Disabilities - Well known people with disabilities and conditions who contributed to society.


List of awareness ribbon colors and their meaning. Also see our calendar of awareness dates.


Blood Pressure Chart - What should your blood pressure be, and information on blood group types/compatibility.



1 - A More Complete Mediterranean Diet May Protect Against Aggressive Prostate Cancer
2 - U.S. Mortality Rate Improvement Slowed by Rise in Obesity
3 - Delta Introduces Enhanced Requirements for Customers Traveling with Service or Support Animals
4 - Virtual Reality Goes Magnetic with Electronic 'Skin' Sensors



Citation


Disclaimer: This site does not employ and is not overseen by medical professionals. Content on Disabled World is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a physician or other qualified health provider with any questions you may have regarding a medical condition. See our Terms of Service for more information.

Reporting Errors: Disabled World is an independent website, your assistance in reporting outdated or inaccurate information is appreciated. If you find an error please let us know.