There is converging evidence of the role of catecholamine dysregulation in the underlying
pathophysiology of attention-deficit/hyperactivity disorder (ADHD). The dopamine transporter
(DAT) is known to be a key regulator of dopamine, and recent genetic, treatment, and
imaging studies have highlighted the role of DAT in ADHD. There is an emerging literature
on in vivo neuroreceptor imaging of DAT in ADHD and control subjects reported by a
number of groups internationally. A comprehensive review of existing imaging studies
of DAT binding in ADHD shows that six of eight independent studies by six different
groups have reported increased DAT binding in (mostly) treatment-naïve children and
adults with ADHD. Although there is fair agreement regarding the presence and direction
of abnormal DAT binding, there remains disagreement as to the magnitude of the finding
and the importance of many potentially confounding variables, including clinical characteristics
and imaging methodology. Three studies by three different groups have reported decreased
DAT binding after methylphenidate treatment. Interpretation of the latter finding
awaits clarification of the issue of timing of drug administration and imaging to
disentangle receptor occupancy from downregulation.
Key Words
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Article info
Publication history
Accepted:
March 29,
2005
Received in revised form:
March 29,
2005
Received:
December 2,
2004
Identification
Copyright
© 2005 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
