Having described three clusters of learning and psychiatric disorders that very often overlap with ADD syndrome, we now return to the question I raised earlier in this chapter. Why is it that having ADD substantially increases the likelihood of having another disorder? Why is it that a child with ADHD, if untreated, has twice the risk of developing a substance use disorder at some time in his or her life? Why do children with ADHD have double or triple the risk of having reading disorder, math disorder, or disorder of written expression? Why do adults with ADHD have additional psychiatric disorders at six times the rate reported for the general U.S. population? Many researchers and clinicians point to genetics, as though one afflicted with ADHD is just unfortunate in being much more likely to be burdened with the inheritance of additional disorders of learning, emotions, or behavior. But there is another way to look at the high incidence of overlap between ADD syndrome and other learning and psychiatric disorders. Rather than considering ADD as just one separate disorder among others, this syndrome might be seen as a cluster of impairments that cuts across other diagnostic categories. To return to our oft-used metaphor, we could say that while a very weak brass section might impair the orchestra's playing of scores strongly reliant on brass, this weakness would not affect the orchestra's work as much as would having a conductor who had chronic difficulty in organizing and directing the musicians. A poor conductor can handicap the entire orchestra, especially when sections of the orchestra are required to play together. Many psychiatric disorders involve such high levels of coordination.
Put another way, executive functions are basic and essential to the integrated operation of many diverse activities of the mind; consequently, individuals with weaknesses in the development of their executive functions are likely to be more vulnerable to many other types of psychiatric impairment, just as anyone with weak bones is more vulnerable to fractures and one with a weak immune system is more vulnerable to a wide variety of infections.
Indeed, impairments of the ADD syndrome described in this book are not specific to ADHD; they occur in many other disorders as well. In 2002 Joseph Sergeant and colleagues published an article asking "How Specific Is a Deficit of Executive Functioning for Attention Deficit/Hyperactivity Disorder?" They noted that whereas children, adolescents, and adults with ADHD have been shown in many studies to have performance deficiencies on some executive-function tasks and tests, similar impairments had been shown in individuals with other disorders—for example, oppositional defiant disorder, conduct disorder, Tourette's syndrome, learning disorders, and high-functioning autism. The article concluded: "EF specificity for ADHD remains to be established" (p. 24).
I would argue that impairments of executive function are not likely ever to be established as specific to ADHD, because most other psychiatric disorders involve both executive-function impairments and additional dysfunctions of more specific cognitive systems. Thus an individual with reading disorder has impairments of executive functions such as working memory as well as specific problems in aspects of the brain involved in decoding and understanding words. A person with Asperger's disorder not only has impairments of executive functions involved in shifting focus, managing emotions, and monitoring action, but also has more specific disruptions in aspects of the brain that are essential for noticing and monitoring emotional communications of others.
In fact, it does not make much sense to think of such combinations of impairments, some of which involve executive functions, as chance occurrences of separate disorders. The situation is not like having a sprained ankle and influenza at the same time. Rather, impairments of executive function might be compared to disruptions of the operating system of a computer that interferes in various ways with running a wide range of software.
Was this article helpful?