Attention Deficit Hyperactivity Disorder

ADHD: definition, diagnosis, prevalence

Editor's Note, December 26, 2011:
I strongly urge the reader to obtain a copy of Anatomy of an Epidemic, by Robert Whitaker. It provides overwhelming evidence, citing many large studies done in the
U. S. and other nations, that drug treatment for psychiatric disorders tends to worsen mental illness, and to turn brief, treatable episodes into chronic mental illness.

Children who are excessively active, are unable to sustain their attention, and are deficient in their impulse control to a degree that is deviant for their developmental level are now given the clinical diagnosis of attention-deficit/hyperactivity disorder. Incidence is approximately 3% - 7% of school-age children.

History of the disorder
In 1902, George Still described a group of 20 children in his clinical practice whom he defined as having a deficit in "volitional inhibition". Still described many of the associated features of ADHD that are corroborated at this time: 1) mail to female ratio of 3 to 1; 2) incidence of alcoholism, criminal conduct, and depression among the biological relatives; 3) a familial predisposition to the disorder implying heredity in some cases;
4) the possibility of the disorder also arising from acquired injury to the nervous system. Children surviving the encephalitis epidemics of 1917-1918 were noted to have many behavioral problems similar to those comprising contemporary ADHD. This gave rise to the concept of the brain-injured child syndrome that would come to be applied to children manifesting the same behavioral features but without evidence of brain damage. This gave rise to the concept of "minimal brain damage", and later, to that of "minimal brain dysfunction" (MBD).
In the '50s and '60s, there was interest in the more specific behaviors of hyperactivity and poor impulse control, labeling the condition "hyperkinetic impulse disorder" and attributing it to cortical overstimulation due to poor thalamic filtering of stimuli entering the brain. This marked a shift away from the conclusion that such symptoms indicated brain damage and toward a more descriptive view of the disorder. This gave rise to the diagnostic term "hyperactive child syndrome", which was said to be typified by daily motor movement far in excess of that seen in normal children of the same age. The belief continued among researchers of that era that the condition had some sort of neurological origin. However, the influence of psychoanalytic thought the time, along with the belief that children's mental disorders necessarily arose as a reaction to various environmental factors, particularly early events in the family life of the child, resulted in the description in DSM-II of "hyperkinetic reaction of childhood". It was defined briefly: "this disorder is characterized by overactivity, restlessness, distractibility, and short attention span, especially in young children; the behavior usually diminishes in adolescence."

By the 1970s, research emphasized the importance of problems with sustained attention and impulse control in addition to hyperactivity. In the '80s, a more complex understanding of the disorder recognized four major deficits: 1) investment, organization, and maintenance of attention and effort; 2) ability to inhibit impulse of behavior;
3) ability to modulate arousal levels to meet situational demands; 4) unusually strong inclination to seek immediate reinforcement.
The disorder was retitled "attention-deficit disorder" (ADD) in 1980 in DSM-III. More explicit criteria were now provided; symptom lists and cutoff scores were recommended for each of three major symptoms (hyperactive, impulsive, inattentive) to assist with identification of the condition. DSM-III now distinguished between two types: with hyperactivity and without it. The current diagnostic model in DSM-IV provides for the separate diagnosis of symptoms relating to inattention, and to hyperactivity and impulsivity.
During the '80s and '90s, research has challenged the notion that ADHD is primarily a disturbance in attention. Results have indicated problems with motivation generally, and an insensitivity to response consequences specifically (Haenlein & Caul, 1987). Russell Barkley (1997, p.8) interpreted these results: "when rules specifying behavior were given that were in conflict with the prevailing immediate consequences in the settings that were available for other competing forms of action, the rules did not control behavior in children with ADHD as well as they did in normal children."
In the '90s, problems with response inhibition and motor system control were more reliably demonstrated and appeared to be specific to this disorder; problems specific to attention seemed harder to demonstrate. It appeared that hyperactivity and impulsivity were not separate symptoms but rather a single dimension of behavior, which Barkley(1997) refers to as disinhibition. This research led to the creation of two separate lists of items and thresholds for ADHD when the DSM-IV diagnostic criteria were published: one for inattention, and another for hyperactive-impulsive behavior. This has permitted the diagnosis of three sub-types of ADHD: ADHD-C, combining attention and hyperactive-impulsive; ADHD-I, predominantly inattentive type; ADHD-HI, predominantly hyperactive impulsive. Top Of Page

DESCRIPTION AND SYMPTOMS

Inattention:
Compared to children of the same age, ADHD children have less ability to sustain attention, respond to tasks or play activities, follow-through on rules and instructions, are more disorganized, distracted, and forgetful. They are less persistent in performing boring activities, such as continuous performance tasks. ADHD children are not generally more distracted by extraneous events occurring during task performance, although they may be distracted if irrelevant stimuli are embedded within the task itself. The symptoms may first be noted at ages five to seven years, possibly later, especially in the case of ADHD predominantly inattentive type.

Hyperactive-Impulsive Behavior (Disinhibition)

Compared to children of the same age, ADHD children are objectively more active than other children, less mature in controlling motor overflow movements, less able to stop ongoing behavior, talk more and interrupt others' conversations, less able to resist immediate temptation and delay gratification, and respond too quickly, as seen in impulsive errors on continuous performance tests. Differences in activity and impulsiveness are found between children with ADHD and those with learning disabilities and other psychiatric disorders. The symptoms are first observed around three to four years of age. Symptoms relating to hyperactivity-impulsivity typically decline in severity with advancing age. Symptoms relating to inattentiveness are more persistent, but generally appeared to decline by adolescence. This pattern may well be to some extent an artifact of the expectations of normal behavior and demands made upon children at various ages. Children under 3 yrs are normally more impulsive and hyperactive; until children enter school, few serious demands for sustained attentiveness and task completion are made.

Other characteristics: situational and contextual factors
(Any model would have to account for these and more)

*Greater variability than normals in performance on continuous performance tasks. *Symptoms vary with context: ADHD children can play video games for prolonged periods of time, but not sustain attention to schoolwork or chores.
*Improved performance on laboratory tasks in the presence of an adult.
*Fatigue or time of day.
*Extent of restraint demanded for context.
*Level of stimulation within the settings.
*Schedule of immediate consequences associated with task.
*Executive function impairments: motor coordination, sequencing, digit span and mental computation, planning and anticipation, verbal fluency, effort allocation, organizational strategies in tasks, internalization of self-directed speech, adhering to restrictive instructions, self regulation of emotional arousal, less mature or diminished moral reasoning. Top Of Page

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Barkley's Critique of the DSM-IV Criteria in regarding to the developmental nature of ADHD: [from Barkley, Russell A (1997). ADHD and the Nature of Self-control (1997). New York: The Guilford Press.
An excellent comprehensive resource for theory and references. Barkley does take the view that ADHD is entirely biological and should be treated with Ritalin, but does provide as complete a single resource as I have found.]

It is not clear that ADHD-I (inattentive) is actually a subtype of ADHD, sharing a common attention deficit with the other types. It is also unclear whether ADHDHI is really a separate subtype from ADHD-C or simply an earlier developmental stage of it. The former is mostly found in preschool-age children, while the latter is seen mostly in school-age children. One would expect this given that hyperactive-impulsive symptoms appear first, followed by those of inattention.

This also raises the issue of whether or not the requirement for significant inattention to diagnose ADHD is even necessary in the case of younger children. However, it must be noted that follow up studies tend to show that the hyperactive-impulsive symptoms, although often emerging before those of inattention, declined more sharply with age than do those of inattention. Such apparent contradictions need to be addressed and explained by any new theoretical model of the disorder. The present view of ADHD gives no clue to the resolution of such findings.

Another problem is how well the diagnostic thresholds established for the symptom lists apply to age groups outside of those used in the DSM-IV field trials (ages 4-16 years, chiefly). If ADHD is a category of pathology than a listing of its symptoms should suffice to define it across the lifespan. But if ADHD is a psychological trait that is dimensional in nature and varies in degree in the normal population, and if that essence is not one of attention or some other developmental process, than the approach taken in DSM will fall short. The same lists and thresholds will not apply equally well across development. Abilities that are developmental in nature can vary in their manifestations at different developmental stages even though the same underlying mental ability is at work in each stage. Mental retardation is a good analogy. It is a deficiency defined as such relative to one's peer group and to an individual's stage of development on measures of intelligence and adaptive functioning. If it were defined and diagnosed like ADHD using a fixed set of items and thresholds developed exclusively on children it might be useful for identifying children as having M. R. upon entry into school-age, but would fail at diagnosing adolescents or adults having mild to moderate MR.

ADHD, like MR, has come to be viewed as a developmental disorder. Therefore, the same types of adjustments to the diagnostic criteria for ADHD may need to be made as has been done for MR.

When symptoms of ADHD persisting into adulthood are assessed by self-report using DSM criteria, persistence into adulthood was only three percent. When age-adjusted definitions were used, again just with self-reported symptoms, the persistence increased to 28 percent. Using the same adjusted criteria, parent reports yielded a persistence of 58 percent.

This definitional problem likely has much to do with the apparent high rate of recovery from the disorder. Top Of Page

	ADHD
Attention Deficit Hyperactivity Disorder
References DSM-IV Description & Symptoms Other Perspectives (Intro Page) Russell Barkley's Critique of DSM-IV Neurological Model Drug Reactions (Breggin) Barkley's Model