New potential leads in the biology and treatment of attention deficit-hyperactivity disorder.

PURPOSE OF REVIEW: This review highlights recent neuroimaging and genetic studies of attention deficit-hyperactivity disorder that may inform biologically targeted interventions and treatments. RECENT
FINDINGS: 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.
SUMMARY: 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.