This review highlights recent neuroimaging and genetic studies of attention deficit-hyperactivity disorder that may inform biologically targeted interventions and treatments.
The findings suggest that attention deficit-hyperactivity disorder is characterized by specific learning and cognitive deficits due to abnormalities in dopamine-rich prefrontal circuitry, of genetic or environmental origins. In addition to prefrontal cortical areas, the basal ganglia, cerebellum, and parietal cortex have been implicated in the condition. These regions are part of unique circuits that project both to and from the prefrontal cortex, thus providing a means for signaling prefrontal regions when top-down control of behavior needs to be imposed. Ineffective signaling of control systems by any one of these regions can lead to poor regulation of behavior. Likewise, intact signaling but inefficient top-down control could result in poor regulation of behavior.
Identification of which cognitive and neural processes are altered in attention deficit-hyperactivity disorder and acknowledgement of different casuses of the condition will lead to more individualized, biologically targeted interventions and treatments. This new direction in research and treatment has occurred as the result of a shift from diagnosis as a phenotype, to refined phenotypes of core cognitive deficits that can be more easily tied to the underlying biology.
aSackler Institute for Developmental Psychobiology, Weill Medical College of Cornell University, New York, New York
bDepartment of Psychology, Michigan State University, East Lansing, Michigan, USA
cRudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
Correspondence to B. J. Casey, Sackler Institute for Developmental Psychobiology, Weill Medical College of Cornell University, 1300 York Avenue, Box 140, New York, NY 10021, USA Tel: +1 212 746 5832; fax: +1 212 746 5755; e-mail: firstname.lastname@example.org