Overflow movements predict impaired response inhibition in children with ADHD.

Full Abstract

Neurologic models proposed to explain mechanisms underlying ADHD have emphasized deficits in response inhibition. Age-inappropriate overflow movements, e.g., mirror movements, are motor signs thought to reflect immaturity in cortical systems involved in automatically (unconsciously, without explicit effort) inhibiting extraneous movement. We investigated the hypothesis that the presence of excessive overflow movements would predict measures of conscious, effortful response inhibition (conflicting and contralateral motor response tests) in children with ADHD. 42 children with ADHD and 30 controls, ages 8 through 12 years, participated. Children with ADHD showed significantly more overflow movements than did controls and made more errors on the conflicting and contralateral motor response tests. Multiple linear regression analysis indicated that overflow movements predicted performance on measures of motor response inhibition. For one of those measures, the contralateral motor response test, there was a significant interaction with diagnosis, such that overflow predicted response inhibition in ADHD but not in controls. The findings suggest that overflow movements, which can be readily observed as part of clinical examination, are more evident in children with ADHD. Positive correlations between measures of overflow movements and measures of response inhibition suggest that closely associated neural mechanisms underlie these deficits and support hypotheses that age-inappropriate overflow reflects immaturity of cortical systems involved in automatic inhibition.

Author information

Author/s: Mostofsky, Stewart H (SH); Newschaffer, Craig J (CJ); Denckla, Martha B (MB);

Affiliation: Kennedy Krieger Institute, Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. mostofsky(-atsign-)kennedykrieger.org

Grants: K08NS02039 (Agency:NINDS NIH HHS) ; M01 RR00052 (Agency:NCRR NIH HHS) ; P30 HD-24061 (Agency:NICHD NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, U.S. Gov't, P.H.S.

Journal: Perceptual and motor skills (Percept Mot Skills), published in United States. (Language: eng)

Reference: 2003-Dec; vol 97 (issue 3 Pt 2) : pp 1315-31

Dates: Created 2004/03/08; Completed 2004/04/23; Revised 2007/11/14;

PMID: 15002876, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

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