Russell A. Barkley, PhD

Attention-deficit/hyperactivity disorder (ADHD) has received an extraordinary amount of attention in the popular media over the past eight months. Stories concerning the disorder, and especially its treatment with stimulant medication, have appeared in many major newspapers, news magazines and television news, entertainment and talk show programs. Such widespread news coverage, as well as the success of parent support associations in disseminating information on ADHD and recent best-selling books on the topic, ensured that clinicians would be called upon increasingly to evaluate, diagnose and manage individuals with this disorder.  

Those services might seem relatively simple and straightforward to the uninitiated, especially given that ADHD has been recognized for quite some time. Explicit criteria for its diagnosis have been available for nearly 16 years in the 

Diagnostic and Statistical Manual for Mental Disorders (DSM) 

and practice guidelines for the evaluation and treatment of ADHD have been disseminated by the American Academy of Child and Adolescent Psychiatry. This, along with several thousand scientific papers and books on the subject, might suggest that the nature of ADHD, its diagnosis and management have been about as well-specified as any childhood disorder to date. 

Such complacency, however, would be wrong. There is much that is new or newly emerging about the nature of this disorder, as well as the most effective approaches to its management. Several hundred new scientific papers on ADHD appear in our scientific journals each year, and there is a good deal of excitement and promise in several "cutting edge" areas of research such as behavioral genetics, neuroimaging and neuropsychology. All of this is challenging and changing our understanding of this disorder, its diagnosis and its management. My purpose here is to highlight some of these advances in understanding ADHD and the changes they may herald for the clinical care of children (and even adults) with ADHD. Space permits highlighting only a few here, however.  

For several decades, clinical wisdom has held that ADHD comprises three primary symptoms: inattention, hyperactivity and impulsivity. While not constituting a scientific theory, this descriptive view nevertheless proved practical in the yeoman's work of explaining the disorder to others (patients, family members, etc.) and reasonably represented the findings of the scientific literature of the time. As in any vibrant area of science, however, additional findings began to overtake this view, calling into question its adequacy for representing or accounting for the newly emerging findings in the scientific literature. These findings also stressed the need for some type of overarching theoretical or conceptual model of ADHD apart from just the clinical description set forth in the 

. Significant among these trends in research were the following, all of which challenged the current descriptive approach to ADHD (Barkley, in press).  





 First, the inattention seen in ADHD may not be the first set of problems to arise in development-hyperactive-impulsive symptoms seem to emerge first, typically in the preschool years. Second, the hyperactive and impulsive symptoms are not two primary or independent constructs but form a single deficit (now called hyperactivity-impulsivity in 

), which I have come to call disinhibition (Barkley 1990). 

Third, the inattentiveness seen in the hyperactive-impulsive (HI) and combined types of ADHD is not in the "input," or information-processing aspects of neuropsychological functioning where attention is often thought to reside, but more likely in the "output," or response-programming and execution aspects.  

Related to that point is a fourth: the inattention seen in children with ADHD, predominantly inattentive (PI) type- also known as ADD without hyperactivity- may actually be a qualitatively different problem than the type of inattention seen in ADHD, HI or combined types- a problem with focused/selective attention versus one of poor goal-directed persistence and interference control (inhibiting distraction) (Barkley, in press; Barkley and colleagues; Goodyear and Hynd; Lahey and Carlson).  

All of this leads to interesting implications for the nature of ADHD, chief among which is that we have possibly two separate and qualitatively distinct disorders on our hands. The PI type may be the true attention disorder while the other two types are simply different developmental stages of the same disorder, one that involves behavioral disinhibition that ultimately results in poor goal-directed persistence and defective resistance to distraction (Barkley, in press). 

If research continues to support such a distinction, it is quite likely that the diagnostic criteria for each should be separate, with a new list of inattentive symptoms created to more accurately reflect this qualitative distinction of the PI type from the other types. Certainly a different name for this new disorder would be needed (say, attention-deficit disorder) that distinguished it from ADHD (which might better be called behavioral inhibition disorder, or BID). And this new ADD would probably be removed from the metacategory of the disruptive behavior disorders as it seems to share little if any comorbidity with oppositional defiant or conduct disorders, as do the other types of ADHD (BID).  

The treatments for these two disorders may prove to be different as well. This is already hinted at in several studies of stimulant medication with these subtypes. There, the PI type has shown a lower rate (prevalence) of positive response to medication (65 percent versus 92 percent), a smaller magnitude or degree of positive response when one is seen, with the most optimal dose being toward the lower end of the therapeutic range as compared to moderate or higher doses (Barkley and colleagues 1991). Should further research replicate these initial findings, it will indicate that stimulants may not be the medications of choice for the PI type of ADHD; their response is hauntingly familiar to that seen in normal children placed on stimulants (Rapoport and colleagues). And while various behavioral or contingency management interventions may still be of assistance for the PI type, they are likely to be so for reasons that are different from why they are needed and helpful in the management of the HI or combined types. The cognitive behavioral therapies may even prove more useful for the PI type although they were of questionable efficacy for the HI or combined types (Abikoff; Diaz and Berk). 

The second conclusion that might be drawn from the foregoing discussion is that the HI and combined types are more reflective of a deficit in behavioral or response inhibition than of inattention. There is substantial support for this conclusion in the extant literature and it is increasing with each new study of response inhibition in ADHD (Barkley, in press; Pennington and Ozonoff). The importance of such a change in perspective on ADHD cannot be overemphasized. 

Research in developmental psychology and neuropsychology have shown behavioral inhibition to be critical to the effective performance of several cognitive abilities considered executive functions because they are related to self-regulation. Not surprisingly, then, researchers in ADHD have begun to view ADHD as a disorder of self-regulation (Douglas) or executive function (Denckla), although both terms are vague when employed in this regard.  

Nevertheless, the trend to a broader conceptualization of ADHD seems necessary given the variety of studies that either demonstrate or at least hint that ADHD children have deficits in working memory and sense of time; the cross-temporal organization of behavior; the internalization of speech and rule-governed behavior; the self-regulation of emotion and motivation; and the execution of complex, novel behavioral sequences (Barkley, in press). All of these are deemed executive functions and all seem to permit control of behavior by internally represented information.  

Far more research is needed on these cognitive functions to cement their association with ADHD. However, the extant research offers the exciting possibility that ADHD is actually a developmental disorder of self-regulation, arising from a deficit in behavioral inhibition that in turn causes a deficiency in behavior regulation by internally represented information or events. If so, the hyperactivity and "inattention" (poor persistence/distractibility) seen in ADHD children and adults may simply be the most obvious (and most superficial) signs of a deeper, more pervasive, more socially significant disorder than has heretofore been imagined. 





 What are the clinical implications of such a shift in conceptualizing the nature of ADHD, should it transpire? Too many exist to list here, but several important ones deserve mention. First, ADHD would be viewed as a disorder of "doing what you know, not knowing what to do," of the "when" of behavior, not the "how," and of performance, not skill. If ADHD involves deficient inhibition that disrupts the regulation of behavior by internally represented information, it attacks the capacity to put intelligence into action. Clinically, this means that training ADHD patients in skills presumed to correct or compensate for their deficits should be deemphasized in most cases as it would be predicted not to work. Perhaps this accounts for the failure of cognitive therapies and other skills-training approaches to generalize outside the training context or to be maintained over time. 

Instead, great emphasis would be placed on helping ADHD individuals do what they know; that is, to perform the skills already in their repertoire at the points of performance where such skills are useful to execute. Useful treatments, therefore, would be those that are in place at these points of performance in natural settings to help prompt use of the skill when it is needed and to reinforce its occurrence so as to maintain it (Ingersoll and Goldstein). From this perspective, weekly, clinic-based therapy hours, whether group or individual in nature, would be considered to be of little value for those with ADHD. Instead, working with parents and teachers to set up behavioral performance programs in natural settings would be more heavily emphasized. The role of mental health professionals shifts from that of direct therapist to the ADHD client to that of consultant to natural caregivers trained to carry out the treatment program in the client's natural social environment. 

A second implication is that the behavioral inhibitory deficit is not wholly correctable through training or other psychosocial treatment methods. It is not likely to fall within the realm of volition or self-control but precedes such self-regulation and even permits it to occur. If so, training a child with ADHD to be less impulsive may be misguided, as we can now appreciate that ADHD disrupts the very neuropsychological mechanism that permits the training to serve as an internal template that effectively executes the associated responses at the right time. Time, timing, internally guided response execution and its persistence become far more important targets for treatments than does knowledge or skill. 

 



 A further implication of such a conceptual shift is that stimulant medications, on the rise over the past decade, may be far more justifiable as a primary or central form of treatment for ADHD than was previously thought. 

Until recently, many practitioners were trained or advised to consider behavioral and psychosocial treatments first before leaping too quickly for the prescription pad to dash off a recommendation for stimulants. Those who did so, even if justifiable by virtue of an absence of such alternative (and expensive) therapies in their geographic regions, may have suffered great pangs of conscience that the now almost proverbial "multimodal" treatments were not applied in such cases. Reconceptualizing ADHD as a developmental disorder of self-regulation (read 

) related to defective motor inhibition for which stimulants have repeatedly proven the most effective management methods challenges this older clinical wisdom. 

An increasing number of behavioral genetic studies of ADHD consistently show it to have a large genetic contribution (averaging 70 percent to 80 percent) and an extraordinarily modest contribution of shared environmental factors (averaging 5 percent to 10 percent). Coupled with recent neuroimaging studies localizing ADHD to the prefrontal lobes and striatum, one has even further justification for at least considering medication treatments for ADHD. 

The totality of the evidence on ADHD, then, may justify considering stimulant medications as a first-line treatment for many (though not all) cases of ADHD. This may relegate psychosocial treatments to the adjunctive status once held by stimulant medication. Apart from any conceptually driven shift in treatment priorities, such a reordering of those priorities may already be occurring, for a more pragmatic reason: the disappointing results of research programs studying nearly ideal multimodal treatment programs have begun to be reported at scientific meetings. While one is typically obliged to still chant that "medication should never be used alone," continued findings along the current direction in treatment research for ADHD may serve to muffle the chant. 

Such findings would lift some of the guilt faced by practitioners, particularly in rural settings with little or no access to multimodal care, concerning their predominant or even singular use of stimulant medication for their patients with ADHD. They could at least know that the one treatment they do have available is turning out to be the most effective for the majority of ADHD children (and adults) under their care.

 



 Moreover, such a shift in treatment priorities also reveals the superficial nature with which most of the popular media have approached the methylphenidate (Ritalin) story over the past year. Such accounts rarely reflect the true complexities inherent in the rise in stimulant use. Instead, many writers seemingly prefer to cast the story as a sporting event, creating scandal where little or none likely exists, sensationalizing the presentation in true tabloid fashion.  

The work of antimedication prophets- typically from outside the mainstream of legitimate scientific research- has appeared alongside that of the far more highly credentialed scientists who have maintained that, within our science at least, there exists little or no "Ritalin controversy." Though this format may have created the facade of balanced journalism, it grossly misrepresented the true status of the clinical scientific literature, reflecting a serious scientific illiteracy on the part of some journalists. The stimulant medications have demonstrated their efficacy in several hundred well-controlled scientific studies, making them not only one of the few success stories in child psychiatry this century but the best-studied of any psychiatric (and other) medication prescribed for children.  

Thus, from the standpoint of both the treatment efficacy literature and the potentially shifting reconceptualization of ADHD noted earlier, a rise in medication use for ADHD would not only be expected, but justifiable. If 5 percent to 7 percent of the childhood population (Szatmari) has ADHD and stimulant medications are proving to be our most effective management methods, then reports that 1 percent to 2 percent of school-age children are taking stimulant medications would not, by itself, be cause for scandal. From a public health perspective, one might say that the real disgrace arises in the untreated percentage, for it is suggested that the most effective tools of management for the disorder are not being used by the majority of those afflicted with it. 





 Many stories simply fail to place the rise in stimulant use in historical context and to explore the topic with a sense of proportion, as journalist James Fallows so often criticizes his colleagues for doing (e.g., his 

Breaking The News: How the Media Are Undermining American Democracy

, recently published by Pantheon Books). Like "stenographers with amnesia," many of these reports fail to note that their own periodicals or television programs reported a mere year or so earlier that the scandal then was the impending shortage of Ritalin for needy and disabled ADHD children. And nearly all failed to see the adversarial relationship between the Drug Enforcement Agency and CH.A.D.D. (Children and Adults with Attention-Deficit Disorder), the largest advocacy and support association for ADHD involved in both of these stories.  

Practitioners should realize that the scientific and theoretical literature on ADHD is changing rapidly, amassing large amounts of published research at a striking pace. Staying abreast of that literature is critical- through newsletters, periodic workshop attendance, national conferences, abstract services or journal subscriptions. The changing world view of ADHD and its treatment have significant clinical and social implications deserving of not only scientific but wider public debate as well.  

If research increasingly points to ADHD as a predominantly inherited disorder of human self-regulation, a story of great social import should be told. Even more widespread, however, should be the findings that genetics makes a disproportionately large contribution to the variation in self-control observed in the population. But the issues raised therein cannot get the public attention or debate they deserve if much of the popular media persist in putting sizzle over substance, petulance over proportion and controversy over context.

Abikoff H. An evaluation of cognitive behavior therapy for hyperactive children. Advances in Clinical Child Psychology, Vol. 10. New York: Plenum; 1987. 

Barkley RA. Attention-Deficit/Hyperactivity Disorder: A Handbook for Diagnosis and Treatment. New York: Guilford Press; 1990.

Barkley RA. Behavioral inhibition, sustained attention and executive functions: constructing a unifying theory of ADHD. Psychol Bull. 1996; in press.

Barkley RA, DuPaul GJ, McMurray MB. Attention- deficit disorder with and without hyperactivity: clinical response to three doses of methylphenidate. Pediatrics. 1991;87(4):519-531.

Barkley RA, Grodzinsky G, DuPaul GJ. Frontal lobe functions in attention-deficit disorder with and without hyperactivity: a review and research report. J Abnorm Child Psychol. 1992;20:163-188.

Denckla MB. Biological correlates of learning and attention: what is relevant to learning disability and attention-deficit/hyperactivity disorder? J Dev Behav Pediatr. 1996;17:114-119.

Diaz RM, Berk LE. A Vygotskian critique of self-instructional training. Development and Psychopathology. 1995;7:369-392.

Douglas VI. Cognitive deficits in children with attention-deficit disorder with hyperactivity. In: Bloomingdale LM, Seargeant J, eds. Attention-Deficit Disorder: Criteria, Cognition, Intervention. New York: Pergamon; 1988.

Goodyear P, Hynd G. Attention-deficit disorder with (ADD/H) and without (ADD/WO) hyperactivity: behavioral and neuropsychological differentiation. J Clin Child Psychol. 1992;21:273-304.

Ingersoll BD, Goldstein S. Attention-Deficit Disorder and Learning Disabilities: Realities, Myths and Controversial Treatments. New York: Doubleday; 1993.

Lahey BB, Carlson CL. Validity of the diagnostic category of attention-deficit disorder without hyperactivity: a review of the literature. In: Shaywitz SE, Shaywitz B, eds. Attention-deficit disorder comes of age: toward the twenty-first century. Austin, Texas: Pro-Ed; 1992.

Pennington BF, Ozonoff S. Executive functions and developmental psychopathology. J Child Psychol Psychiatry. 1996;37:51-87.

Rapoport JL, Buchsbaum MS, Zahn TP, et al. Dextroamphetamine: cognitive and behavioral effects in normal prepubertal boys. Science. 1978;199(4328):560-563.

Szatmari P. The epidemiology of attention-deficit/hyperactivity disorders. In: Weiss G, ed. Child and Adolescent Psychiatric Clinics of North America: Attention-Deficit Disorder. Philadelphia: W.B. Saunders; 1992. 

Articles

Attention-deficit/hyperactivity disorder (ADHD) has received an extraordinary amount of attention in the popular media over the past eight months. Stories concerning the disorder, and especially its treatment with stimulant medication, have appeared in many major newspapers, news magazines and television news, entertainment and talk show programs.

Russell A. Barkley, PhD

Articles

Research Developments and Their Implications for Clinical Care of the ADHD Child