ATTENTION-DEFICIT HYPERACTIVITY DISORDER

Attention deficit hyperactivity disorder (ADHD) is a common disorder in children, characterized by three core-groups of age-inappropriate symptoms:

a. Hyperactivity,

b.Impulsivity, and

c.

Leading to secondary problems, e.g. poor scholastic performance, conduct disorders, emotional and social maladjustment, etc.

While some children have all three components of ADHD, others manifest with abnormalities in only one or two fields. Accordingly, three major types of ADHD are recognized:

a. ADHD, combined type (~60-70%)

b. ADHD, predominantly inattentive type (~25-30%)

c. ADHD, predominantly hyperactive/impulsive type (~8-10%)

Prevalence: Reported prevalence of ADHD varies according to diagnostic criteria, awareness among health professionals and cultural norms of the community. Frequently under diagnosed, ADHD is estimated to be present in ~10% of Indian children, with striking preponderance in boys (4-6:1). Boys are more likely to be hyperactive/impulsive, while girls are usually inattentive.

Pathology: Hypoplasia and hypofunctioning offrontostriatal system is considered as the key pathological defect in ADHD, with altered balance between two important neurotransmitters that modulate attention, mood and movements-neuroinhibitory dopamine and neuro- excitatory norepinephrine.

Modern investigative techniques have shown signi­ficant structural/functional abnormalities in ADHD children including:

a. smaller volumes of frontal lobes and cerebellum,

b. diminished cerebral blood flow,

c. impaired cerebral oxygen/glucose metabolism, and

d. reduced levels or end-receptor sensitivity of dopamine. Etiology of ADHD is uncertain, currently thought to be a complex interplay of both hereditary and environmental factors. Some important causative factors include:

a. Hereditary seems to play a crucial role in ADHD as ~ 1 / 3^rd of these cases have similar family history and concordance rate in monozygotic twins is ~75-90%.

b. Environmental factors seem to be more important in cases without family history. Low birth weight and prenatal exposure to maternal smoking, alcohol/drug abuse and environmental toxins, e.g. lead, dioxins and plastic constituents have been frequently implicated. Other adverse factors in family environment, e.g. psychosocial stress, maternal mental disorder, paternal criminality, low socioeconomic status, etc. have also been linked to the increased risk of ADHD.

Clinical presentations: While the diagnosis of ADHD is usually not made till school entry, most cases have abnormal behavioral traits in earlier life, e.g. excessive crying and disturbed sleep in infancy or even unusual intrauterine activity. Some of them may achieve gross motor milestones at an earlier age.

Hyperactivity/impulsivity is often appreciated earlier (at 4-5 years of age) than inattention (8-9 years). Characteristic core-group manifestations of ADHD are as follows, though all children do not have all components:

a. Inattentiveness, though commonest manifestation is often overlooked in preschool years and rarely noticed before school age. These children have difficulty in focussing their attention in situations that call for sitting still, e.g. classrooms or dinner tables. They can only engage themselves in brief activities and change activities frequently. Children with predominantly inattentive type of ADHD often seem to drift away into their own thoughts or lose track of what was going on around them.

b. Hyperactivity, the commonest cause of parental concern is usually noticed in preschool years as excessive movements, restlessness, fidgety, and shortened attention span. As pre-schoolers by nature have shorter attention span that improves with time, persistence of such behavior beyond 3 years of age is a more reliable indicator of ADHD.

c. Impulsivity is closely associated with hyperactivity and often manifests as a dislike or inability for waiting for his/her turn. They interrupt others in their conversations and some of their actions may be extremely irritating or dangerous. When stimulated, they can quickly get out of control and turn aggressive or abusive.

Comorbidities: Apart from core-group manifestations, ~30-50% of these children have co-existing cognitive, learning and language disorders. Further, most of them develop secondary behavioral problems with advancing age, e.g. oppositional defiant behavior, conduct dis­orders, antisocial behavior and risk-taking behavior like drug abuse, sexual misconduct, teenage pregnancy, etc. Early identification and appropriate intervention for ADHD may prevent these complications in late childhood/adolescence.

Diagnosis: There is no specific diagnostic test for ADHD and diagnosis is exclusively clinical, based on DSM-V criteria (Table 3.19). It should be noted that:

TABLE 3.19: Diagnostic criteria for ADHD (DSM V)*

TABLE 3.20: Guidelines for parents/teachers in ADHD

A. Age-inappropriate behavior (A-1 or A-2) A-1 Inattention (6 or more)

1. Fails to attend details/make careless mistakes

2. Difficulty in sustained attention during tasks

3. Does not seem to listen, when spoken directly

4. Does not follow instructions. Fails to finish task

5. Troubles in organising the tasks

6. Avoids tasks requiring sustained mental efforts

7. Loses things, e.g. toys, books, etc.

8. Easily distracted

9. Forgetful in daily activities

A-2 Hyperactivity/impulsivity (6 or more)

1. Fidgets with hands or feet

2.

3. Runs-about/ climbs in inappropriate situations

4. Difficulty in playing quietly

5. quot;Often on the goquot; as driven by a motor

6. Talks excessively

7. Blurts-out answers before question completes

8. Difficulty in waiting for their turn

9. Interrupts or intrudes on others

B. Some symptoms evident lt;12 years of age

C. Symptoms present in gt;1 situation (home, school)

D. Symptoms interfere in social/school functions

E. Symptoms not accountable to other pervasive developmental or mental disorder

*All 5 criteria (A-E) should be fulfilled.

Note: Classification of ADHD sub-types:

- Combined type: (both A1 and A2 fulfilled)

- Predominantly inattentive type: (only A1 fulfilled)

- Predominantly hyperactivity/impulsivity (only A2 fulfilled)

a. As many of ADHD symptoms are also commonly present in normal preschool children, diagnosis should be reviewed after repeated evaluation and preferably kept as provisional till 5 years of age.

b. Some signs/symptoms of ADHD, e.g. verbal impulsivity and restlessness may not be evident in highly-structured situations, e.g. clinics and their absence does not preclude the diagnosis.

Considering the complex nature of disease, a multi­disciplinary assessment is necessary in all cases of ADHD, including:

a. Detailed perinatal and developmental history,

b. Psychometric testing as well as other standardized rating scales-to be completed by the parents and child's school,

c. Thorough physical examination and developmental assessment,

d. Evaluation for abovementioned diagnostic criteria,

e. Evaluation for co-morbidities or secondary behavioral problems, and

f. Psychosocial evaluation of the family and school environment. Laboratory investigations are indicated only to exclude other causes of hyperactivity/ inattention.

• Ensure a regular routine and environment

• Divide his/her work into small chunks

• Provide simple and clear instructions

• Make frequent eye contacts with child

• Allow liberal breaks between the tasks

• Positive reinforcement: Praise on task completion

• Non-accusatory feedback on task completion

• Avoid overstimulation/fatigue to the child

• Avoid exciting TV programs/games at bed time

• Keep dangerous articles beyond the child's reach

• Be loving but consistent and firm with child

• Encourage peer-relations and teach social skills

• Promote his strengths to build self-confidence

D/D: Although features of ADHD are quite characteristic, transient/persistent hyperactivity or inattention may also be due to: (a) allergies, (b) sleep deprivation, (c) chronic physical disability, (d) sensory impairment, e.g.

Management aims to improve functional outcomes, e.g. decrease hyperactivity and impulsivity levels, improve social and academic functioning, along with treatment of co-morbid conditions. Effective interventions may be broadly divided into two categories: (a) behavioural management, and (b) pharmacotherapy.

Behavioral management should begin as soon as possible, even in pre-school phase before confirmation of diagnosis and should include: (a) Positive reinforcement,

e. g. rewarding the child after successful completion of given task, (b) Negative reinforcement, e.g. withdrawing a reward after an unwanted behavior, (c) Time-outs,

e. g. asking the child to stay away for some time after a unwanted behaviour. Some important guidelines for parents/teachers are given in Table 3.20.

Pharmacotherapy is largely needed for older children and should not be started before the confirmation of diagnosis at ~6-7 years of age and the family has been counselled about purpose of medications, i.e. to control the symptom and not to cure the disease. Parents should be advised that 2-6 weeks of medication may be needed for any therapeutic effect.

Psychostimulants, e.g. methylphenidate (MPH), is the cornerstone of pharmacotherapy in ADHD, which boost and balance the level of neurochemicals, e.g. dopamine and norepinephrine, by facilitating their synaptic release and inhibiting their reuptake. About 70-80% cases show positive response to stimulants as reduced hyperactivity, increased attention span, and improved visual/motor skills. However, these agents do not directly address other problems, e.g. academic failure or social maladjustment.

Dosage and frequency requirements of MPH vary in different children. Usually, therapy should begin with a low dose of PO 5 mg/dose 30 minutes after meals and should be increased gradually to maximum of 60 mg (never gt;2 mg/kg) according to the clinical effect.

Long-term use of MPH is known to cause growth suppression and intermittent drug vacations are recommended to minimize growth effects. A child with the predominantly inattentive type of ADHD may need medication only on school days, while a child with difficulty in peer relationships may need it every day. A child who participates in afterschool academics or sports activities on certain days of the week may require longer-acting preparations or more frequent dosing on those days.

Atomoxetine hydrochloride, a non-stimulant nore­pinephrine transport inhibitor, has been recently established as safe and effective alternative. It should be started with a lower dose of PO 0.5 mg/kg/day for at least first 3 days and gradually increased to maximum 1.2 mg/kg/day. Unlike psychostimulants, which are predominantly useful in hyperactive children, atomoxetine has shown effectiveness in both the inattentive and hyperactive symptoms domains.

Dietary interventions, e.g. elimination of foods considered as allergens, e.g. wheat, milk, eggs, etc. or diets incriminated to increase hyperactivity, e.g. sugar, chocolate and caffeine, etc. are of no proven value, as also the Fein-Gold diet (free of additives).

Prognosis: ADHD is incurable but can be managed successfully in most cases. Hyperactivity/impulsivity usually lessens with age, often replaced by other problems, e.g. antisocial behavior and learning difficulties. Inattention tends to persist throughout the life. In general, 30% children show near-complete resolution of symptoms by adulthood, 40% persist with some symptoms but overall adequate functioning and the rest continue to have severe dysfunction with secondary complications, e.g. anti-social behavior. Adults with childhood ADHD have a higher likelihood of emotional and social problems, unemployment, and criminality.

Unfortunately, ADHD is not recognized as a disability under the Disability Act 1999, as of now.

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