Genetics of Childhood Disorders: XVIII. ADHD, Part 2: Norepinephrine Has a Critical Modulatory Influence on Prefrontal Cortical Function

Abstract

Dysfunction of the prefrontal cortex (PFC) is a fundamental component of attention-deficit/hyperactivity disorder (ADHD). The PFC uses working memory to intelligently guide behavior, inhibiting inappropriate impulses or distractions and allowing us to plan and organize effectively (see previous column). Individuals with ADHD are consistently impaired on tests of frontal lobe function, and both structural and functional imaging studies have shown evidence of altered PFC function in individuals with ADHD. In particular, the right PFC has been shown to be consistently smaller in ADHD subjects than in age-matched controls, and the inability to suppress responses to salient but irrelevant stimuli correlates with reduced volume of the right PFC ( Casey et al., 1997 Casey BJ Castellanos FX Giedd JN et al. Implication of right frontostriatal circuitry in response inhibition and attention-deficit/hyperactivity disorder. J Am Acad Child Adolesc Psychiatry. 1997; 36: 374-383 Abstract Full Text PDF PubMed Scopus (665) Google Scholar ).