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ADHD Module

Description and Characteristics of AD/HD

AD/HD is a neurobiological condition that affects executive functions which are described as the management system of the brain (Brown, 2008). One of the leading researchers of AD/HD, Russell Barkley (as cited in Brown, 2008, p. 17), “has argued that impairment of the ability to inhibit is the primary problem of persons with AD/HD, and, of all of the executive functions impaired in the disorder, is the one on which the development and effective functioning of all other executive functioning depends.” The lack of inhibition of other executive functions is detrimental to a person with AD/HD in terms of focusing or managing other cognitive tasks. Brown outlines executive functions and the impact of AD/HD on these functions in the following graphic:

According to Brown’s (2008) research, “most people with AD/HD report significant chronic difficulties in at least some aspect of each of these six clusters” (p. 13). Related to Barkley’s focus on inhibition, Brown views attention as the central feature of the disorder. The inability to sustain or switch the focus of one’s attention leads to deficits in the other areas of executive function. In other words, “attention is essentially a name for the integrated operation of the executive functions of the brain” (Brown, 2008, p. 12). Attention refers to a dynamic process of determining and engaging in what is important to notice, to do, and to remember, moment to moment (Brown, 2005). Results from a study on individuals with AD/HD showed that a multitude of deficits in attention are present, including selective attention, executive attention, sustained attention, and orienting of attention (Shalev, Mevorach, & Tsal, 2005).

Other characteristics of AD/HD include:

  • Excessive impulsivity
  • Chronic procrastination
  • Excessive distractibility
  • A failure to notice critical details
  • Restlessness or hyperactivity
  • Difficulty getting started on tasks
  • Difficulty completing tasks
  • Frequently losing things
  • Poor organization, planning, and time management skills
  • Excessive forgetfulness

(Brown, 2008; National Resource Center on AD/HD, n.d.)

Individuals with AD/HD are often diagnosed with comorbid or coexisting disorders, including:

  • Learning Disabilities (see the Learning Disability (LD) Module)
  • Oppositional Defiant Disorder
  • Conduct Disorder
  • Anxiety and/or Depression
  • Bipolar Disorder
  • Tourette’s Syndrome

(Brown, 2009; National Resource Center on AD/HD, n.d.)



Brown, T. E. (2005). Attention deficit disorder: The unfocused mind in children and adults. New Haven, CT: Yale University Press.

Brown, T. E. (2008, February). Executive functions: Describing six aspects of a complex syndrome. Retrieved from http://www.chadd.org/AM/Template.cfm?Section=Especially_For_Adults&Templ...

Brown, T. E. (Ed.). (2009). ADHD comorbidities: Handbook for ADHD complications in children and adults. Arlington, VA: American Psychiatric Publishing.

National Resource Center on ADHD. (n.d.) Coexisting conditions. Retrieved from http://www.help4adhd.org/en/treatment/coexisting

National Resource Center on ADHD. (n.d.). Symptoms and diagnostic criteria. Retrieved from http://www.help4adhd.org/en/treatment/guides/dsm

Shalev, L., Mevorach, C., & Tsal, Y. (2005). The diversity of attention deficits in ADHD: The prevalence of four cognitive factors in ADHD versus controls. Journal of Learning Disabilities, 38(2), 142-158.