Different brain dysfunctions in ADHD patients compared to children with conduct disorder
JUNE 04, 2008
Children with Attention Deficit Hyperactivity Disorder (ADHD) and those with Conduct Disorder (CD) are disruptive disorders that are characterised by problems with the inhibitory control of their behaviours. Behaviourally, they overlap in symptoms and in their cognitive profile and are therefore often difficult to differentiate clinically. However, the underlying neurobiology may well be different between the two disorders. Finding specific biomarkers for overlapping childhood disorders is one of the goals of the research team lead by Dr Katya Rubia.
A study to appear in the American Journal of Psychiatry, and now published online in AJP-Advance, compared the underlying neurophysiological substrates of inhibitory control in medication-naïve boys with pure ADHD and in those with pure CD as well as healthy children using functional magnetic resonance imaging while the children were performing a motor inhibition task.
The findings show that the typical dysfunction in boys with ADHD, i.e. underactivation in lateral prefrontal cortex during inhibition, repeatedly observed by this and other research teams, is specific to ADHD and is not observed in boys with CD. By contrast, only boys with CD, but not with ADHD, showed abnormalities in temporal and parietal brain regions.
The results show that children with ADHD and with CD appear to have distinct brain abnormalities that underlie their overlapping behavioural problems. Finding specific biological markers that can distinguish the two disorders can help with the development of differential diagnosis and disorder-specific treatment.
Papers details: Rubia K., Halari R., Smith AB., Mohammad M., Scott S, Giampietro V., Taylor, E., Brammer, M. E. (2008) Dissociated functional brain abnormalities of inhibition in boys with pure Conduct disorder and in boys with pure Attention-Deficit/Hyperactivity Disorder. Am J Psychiatry, in press. http://ajp.psychiatryonline.org/cgi/reprint/appi.ajp.2008.07071084v1