Attention deficit hyperactivity disorder (ADHD) is a common psychiatric disorder in children, characterized by three core-groups of age-inappropriate symptoms hyperactivity, impulsivity and inattentiveness; leading to secondary problems like poor scholastic performance, conduct disorders, emotional and social maladjustment etc.
While some children have all three components of Attention deficit hyperactivity disorder, others manifest with abnormality in only one or two fields. Accordingly, three major types are recognized as combined type (—25%), predominantly inattentive type (—50%), predominantly hyperactive/impulsive type (-25%).
Reported prevalence of Attention deficit hyperactivity disorder varies according to diagnostic criteria, awareness among health professionals and cultural norms of the community. Frequently under diagnosed, It is estimated to be present in 5-10% 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 hypo functioning system is considered as the key pathological defect in Attention deficit hyperactivity disorder, with altered balance between two important neurotransmitters that modulate attention, mood and movements — neuroinhibitory Dopamine and neuroexcitatory Norepinephrine.
Modern investigative techniques have shown significant structural and abnormalities in children like smaller volumes of frontal lobes and cerebellum, diminished cerebral blood flow, impaired cerebral oxygen/glucose metabolism, and reduced levels or end-receptor sensitivity of dopamine.
Exact etiology for these pathological changes 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 Attention deficit hyperactivity disorder as 1/3rd of these cases have similar family history and concordance rate in monozygotic twins is — 75-90%. Genetic studies have implicated defect in several genes, modulating dopamine/norepinephrine action like D2 receptor gene (DRD2), D4 receptor gene (DRD4), and over expression of dopamine transporter-i gene (DAT- 1), all located on short arm of chromosome 16.
b) Environmental factors seem to be more important in Attention deficit hyperactivity disorder children without family history. Low birth weight and prenatal exposure to smoking, alcohol/drug abuse and environmental toxins like lead, dioxins and PCBs (plastic constituents) have been frequently implicated. Other adverse factors in family environment like psychosocial stress, maternal mental disorder, paternal criminality, low socioeconomic status etc. have also been linked to increased risk of Attention deficit hyperactivity disorder.
Clinical presentations: Although the diagnosis of Attention deficit hyperactivity disorder is usually made in pre-school years, most Attention deficit hyperactivity disorder children have abnormal behaviour traits in earlier life like excessive crying and disturbed sleep in infancy or even unusual intrauterine activity. Many of them achieve gross motor milestones at an earlier age.
Characteristic core-group manifestations are as follows, though all children do not have all component
– Inattentiveness, though commonest manifestation is often overlooked in preschool years and and rarely noticed before school-age. These children have difficulty in controlling their activity in situations that call for sitting still like classrooms or dinner tables. They can only engage themselves in brief activities, and change activities frequently. Children with predominantly inattentive type of Attention deficit hyperactivity disorder often seem to drift away into their own thoughts or lose track of what was going on around them.
– Hyperactivity, the commonest cause of parental concern is usually noticed in pre-school years as — excessive movements, restlessness, fidgety, and shortened attention span. As preschoolers 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 Attention deficit hyperactivity disorder. Even in older children and adolescents, attention span often depends on the level of interest in a particular activity. Most teenagers can listen to music or talk to their friends for hours but may be less focused during homework. Hyperactivity tends to increase when child is tired, hungry, anxious or facing a new environment.
– Impulsivity is closely associated with hyperactivity and often manifests as a dislike for waiting for his/her turn. They interrupt others in their conversations and some of their actions may be extremely erratic or dangerous. Some children are extremely sensitive to sensory stimuli like sight, sound and touch. When stimulated, they can quickly get out of control and turn aggressive or abusive.
Co-morbidity: 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 like conduct disorders, antisocial behavior, drug abuse, sexually transmitted diseases, teenage pregnancy etc. Early identification of Attention deficit hyperactivity disorder may prevent these complications in late childhood/adolescence.
There is no specified diagnostic test and diagnosis is exclusively clinical, based on well-defined criteria (Table 4.4). It should be noted that —
a) As many indicators are normally present in pre-school children, diagnosis should be reviewed after repeated evaluation and preferably kept as provisional till 5 years of age.
b) Some signs/symptoms like verbal impulsivity and restlessness may not be evident in highly-structured situations like clinics and their absence does not preclude the diagnosis.
Considering the complex nature of disease, a multidisciplinary assessment is necessary for in all cases of Attention deficit hyperactivity disorder, including Detailed perinatal & developmental history, psychometric testing as well as other standardised rating scales to be completed by the parents and child’s school, thorough physical examination and developmental assessment, evaluation for above-mentioned diagnostic criteria, evaluation for co-morbidities or secondary behavioral problems and psychosocial evaluation of the family and school environment. Laboratory investigations are indicated only to exclude other causes of hyperactivity/inattention.
D/D: Although features of Attention deficit hyperactivity disorder are quite characteristic, transient/persistent hyperactivity or inattention may also be due to mental retardation, seizure disorders like absence seizures, sensory impairment like hearing/visual defects, chronic physical disability, dmg toxicity like anticonvulsants, and sleep deprivation.
Optimum treatment for Attention deficit hyperactivity disorder is a matter of intense debate, although effective interventions may be broadly divided into two categories — a) Pharmacotherapy, b) Clinical behavioural management.
A multi-disciplinary approach involving pediatrician, psychiatrists, psychologist, teachers as well as parents is essential for best results.
a) Pharmacotherapy: Psychostimulants like Methyiphenidate, are the cornerstone of pharmacotherapy in Attention deficit hyperactivity disorder, which boost and balance the level of neurochemicals like 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 address other problems like academic failure or social maladjustment.
Methyiphenidate (MPH) – a dexamphetamine derivative with rapid action, short half-life and wide safety margin is the preferred choice in most cases. Other psychostimulants like dexamphetamine or pemoline are rarely used in pediatric practice.
Dosage and frequency requirements of MPH vary in different children, unrelated to body weight. MPH therapy should begin with low dose of P0 2.5 mg/dose 30 minutes before meals and should be increased gradually to maximum of 60 mg/day, according to the clinical effect. The action begins with 20-30 minutes with peak effect at 1-2 hours and lasts for 3-5 hours.
Side effects like anorexia, headache, abdominal discomfort, mood instability and insomnia (MPH should not be given after 4 PM) are common at the onset of therapy but rarely require dosage modifications and disappear after few days.
Other side-effects like tics or persistent hypertension are rare and may require dose reduction. Clonidine (P0 1-4 mg/kg/d) may be used as adjuvant to reduce side-effects like tics, aggression and sleep difficulties. Long-term use of MPH is known to cause growth suppression and hence, intermittent drug- vacations are recommended to minimize growth effects and re-evaluate the need of further medications. Dependence is rare in children.
A tomoxetine hydrochloride, a non-stimulant norepinephrine transport inhibitor, has been recently established as safe and effective alternative to MPH in clinical trials. Unlike psychostimulants, which are predominantly useful in hyperactive children, atomoxetine has shown effectiveness in both the inattentive and hyperactive symptoms domains.
Tricyclic antidepressants like Imipramine/ Desipramine (P0 1-4 mg/kg/d) are used in children who do not respond to stimulants, develop major side effects or severe co-morbidity like anxiety or depression.
b) Psychosocial interventions are as important as pharmacotherapy in management of these cases and include child’s behavior modifications, as well as parentallteacher training to cope with the problem and enhance child’s potential, using a multidisciplinary approach involving psychiatrist, psychologist, social workers, support groups etc.
Child’s behavior modification is a complex issue and involves need-based strategies like cognitive behavioral procedures to facilitate self-regulated behavior and psychotherapy for secondary Attention deficit hyperactivity disorder. However, efficacy of these interventions is unproven. A stress-reducing biofeedback technique to control body responses via audiovisual stimulation has been shown to be effective in sustenance of drug-induced behaviour control in selected cases.
Parental/teacher behavior mod (fication and training is important as care of these high-energy, inattentive, and impulsive children is usually frustrating and unrewarding.
c) Dietary interventions like elimination of foods considered as allergens like wheat, milk, eggs etc. or incriminated to increase hyperactivity like sugar, chocolate and caffeine etc. are of no proven value, as also the Fein-Gold diet (free of additives).
Attention deficit hyperactivity disorder is incurable but can be managed successfully in most cases. Hyperactivity/impulsivity usually lessens with age, but often replaced by other problems like antisocial 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 like antisocial behavior. Most adults with childhood Attention deficit hyperactivity disorder have emotional and social problems, unemployment, and criminality.
Functional prognosis is better in cases with absence of co-psychiatric conduct disorders at the time of diagnosis, early pharmacotherapy and co-operative or understanding parents/teachers.
Guidelines for parents and teachers in Attention deficit hyperactivity disorder
• Ensure a regular routine & environment
• Divide his/her work into small chunks
• Provide simple & clear instructions
• Make frequent eye contacts with child
• Allow liberal breaks between the tasks
• Positive reinforcement: praise on task completion
• Non-accusatonj 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
Check out the below video from National Institute of Health on Attention deficit hyperactivity disorder (ADHD)