Research article summary (published 12 Sep 2007):

Low blood lead levels associated with clinically diagnosed attention-deficit/hyperactivity disorder and mediated by weak cognitive control.

Full Abstract

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) and low-level lead exposure are high-prevalence conditions among children, and studies of large populations have suggested that these conditions are related. We examine this relationship in children from a community sample exposed to average background levels of lead who have a diagnosis of ADHD that is established by clinical criteria. METHODS: One hundred fifty children ages 8-17 years participated (mean age = 14 years; 53 control subjects, 47 ADHD Predominantly Inattentive type, 50 ADHD-Combined type). Diagnosis was formally established with a semi-structured clinical interview and parent and teacher ratings. Children completed intelligence quotient (IQ) measures and the stop task (a neuropsychological measure). Lead was assayed from whole blood with inductively coupled plasma mass spectrometry. RESULTS: Blood lead levels in this sample closely matched US population exposure averages, with a maximum level of 3.4 mug/dL. Blood lead levels were statistically significantly higher in ADHD-combined type than in non-ADHD control (p < .05) children. Blood lead was associated with symptoms of hyperactivity-impulsivity but not inattention-disorganization, after control of covariates. Blood lead levels were linked with a lower IQ (p < .05), but IQ did not account for effects on hyperactivity. Instead, hyperactivity mediated effects of lead on IQ. Effects of blood lead on hyperactivity-impulsivity were mediated by poor performance on the stop task. This mediation effect was independent of effects of lead on IQ. CONCLUSIONS: Low-level lead exposure might be an important contributor to ADHD. Its effects seem to be mediated by less effective cognitive control, consistent with a route of influence via striatal-frontal neural circuits.

Author information

Author/s: Nigg, Joel T (JT); Knottnerus, G Mark (GM); Martel, Michelle M (MM); Nikolas, Molly (M); Cavanagh, Kevin (K); Karmaus, Wilfried (W); Rappley, Marsha D (MD);

Affiliation: Department of Psychology, Michigan State University, East Lansing, Lansing, MI 48824-1116, USA. nigg(-atsign-)msu.edu

Grants: R21 MH 070542 (Agency:NIMH NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: Biological psychiatry (Biol Psychiatry), published in United States. (Language: eng)

Reference: 2008-Feb; vol 63 (issue 3) : pp 325-31

Dates: Created 2008/01/15; Completed 2008/02/27; Revised 2008/04/02;

PMID: 17868654, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: 18 Feb 2009 00:00:00)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

External Links for this article
(including full text providers, if available):

Click Electronic Full-text Provider Links to see options for finding the electronic full text links to this article. Note there may be a subscription or fee required for access to the full text. See our FAQ for information on finding FREE full text articles.

This article may also be located in paper journal collections available in many libraries. Use the Journal and Publication Information above to find the full article.

MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adolescent Attention Deficit Disorder with Hyperactivity - blood; complications Child Cognition Disorders - blood; etiology Female Humans

Humans Intelligence - physiology Lead - blood Male Mass Spectrometry - methods Neuropsychological Tests

Associated Chemicals: Lead (7439-92-1)

Related articles

These are the highest related articles currently in the database:

• Effects of IQ on executive function measures in children with ADHD. 27 Feb 2002
• Sustained attention and inhibition of cognitive interference in treated phenylketonuria: associations with concurrent and lifetime phenylalanine concentrations. 30 Dec 2001
• The relationship between tic disorders and Tourette's syndrome revisited. 30 Aug 1995
• Deficient inhibitory control in attention deficit hyperactivity disorder. 30 Jul 1995
• [Behavioural and neuropsychological characteristics of children of both sexes, between 6 and 11 years of age, with attention deficit hyperactivity disorder] 30 Jul 2008
• Effects of blood lead levels on cognitive function of older women. 30 Dec 1995
• TSH concentration within the normal range is associated with cognitive function and ADHD symptoms in healthy preschoolers. 30 May 2007
• Results of blood lead screening in children referred for behavioral disorders. 30 May 1997
• Neuropsychological performance in pediatric bipolar disorder. 30 Dec 2003
• [PASS neurocognitive dysfunction in attention deficit] 30 Dec 2000

See 100+ related articles.

Related Article Map

Legend: - FREE Full text Article. - Abstract only. - Title only. More help.

See a large map of 100+ related articles.