| disease | ADHD (Attention Deficit Hyperactivity Disorder) |
| alias | Hyperactive Children, Attention Deficiency Disorder, ADD, MBD, Minimal Brain Dysfunction, Hyperactivity Syndrome, Attention Deficit Disorder, Mild Disorder of Brain Function, Mild Brain Dysfunction Syndrome |
Attention Deficit Hyperactivity Disorder (ADHD), also known as hyperkinetic syndrome of childhood, is a common behavioral disorder in children. It is also referred to as minimal brain dysfunction (MBD) or attention deficiency disorder (ADD). These children typically have normal or near-normal intelligence but exhibit deficiencies in learning, behavior, and emotions. Symptoms include difficulty concentrating, short attention spans, excessive activity, and impulsive emotions, which can negatively impact academic performance. They often struggle to get along with others at home and school, making daily life challenging for parents and teachers. Some liken this disorder to a symphony losing its coordination and harmony. Foreign data reports a prevalence rate of about 5–10%. Domestic studies also indicate a significant number of school-age children affected, accounting for approximately 1–10% of all elementary school students. Boys are far more likely to be affected than girls. Premature labor is associated with a higher incidence of this disorder in children.
bubble_chart Etiology
Attention Deficit Hyperactivity Disorder (ADHD) may have various causes. It is generally believed that grade I brain damage occurring prenatally, during birth, or postnatally is a significant factor, primarily associated with brain trauma, poisoning, and similar conditions. Some suggest that urban environmental pollution and clinically asymptomatic grade I lead poisoning could also be one of the disease causes. Recent surveys and studies comparing the biological parents, adoptive parents, and other pediatric patients of affected children found that certain mental illnesses, such as alcohol addiction and pathological personality traits, were more prevalent among biological parents than in the control group. Parents of children with ADHD were more likely to have a history of hyperactivity during their own childhood, and the siblings of these children had a threefold higher incidence of ADHD compared to the control group, with affective psychosis also being more common. Additionally, fathers of children with ADHD exhibited higher rates of antisocial personality traits or alcohol dependence, while mothers showed a higher prevalence of hysteria. Among children with ADHD comorbid with conduct disorder, adult relatives had even higher rates of personality disorders, alcohol addiction, and hysteria. Studies on adopted children also revealed that biological parents of children with ADHD had significantly higher rates of antisocial personality, alcohol dependence, and hysteria compared to adoptive parents or parents of control group children. Parents of these children were also more likely to have a history of hyperactivity and conduct disorder during their own childhood, as well as psychiatric disorders. The incidence of ADHD was higher in monozygotic twins than in dizygotic twins, and the prevalence among full siblings was about five times higher than among half-siblings, suggesting that mild brain dysfunction in some affected children may be influenced by genetic factors, impacting psychological development. Many children with ADHD have no identifiable disease cause.
Recent accumulating evidence suggests that this disorder has an abnormal neurophysiological basis, proposing that hyperactivity and inattention may be related to insufficient function of the brain's catecholamine system (including norepinephrine, with dopamine as its precursor). Animal experiments showed that when drugs were used to reduce or deplete dopamine levels in rat brains, the animals exhibited hyperactive behavior. Administering amphetamines to increase dopamine levels at synaptic sites and enhance the activity of dopaminergic neurons calmed the animals. Clinically, amphetamines and imipramine (both of which increase dopamine levels at synaptic sites) have been effective in treating hyperactivity in children. In probenecid tests, measurements of dopamine metabolites in the cerebrospinal fluid of affected children were also found to be lower than in the control group.Recent PET studies have found that dopamine receptor density is related to child development, and the specific changes in dopamine receptor density do not mature until adolescence. The area most susceptible to influence in hyperactive children is believed to be the dopaminergic pathways in the frontal lobe. Neuropsychological research suggests that the frontal lobe function in hyperactive children has not fully matured. The prefrontal cortex is thought to be associated with impulsive and aggressive behaviors in children. Measurements have revealed that localized cerebral blood flow in hyperactive children is primarily affected in the frontal lobe and caudate nucleus. Some studies have demonstrated that medication increases blood flow in the basal ganglia and midbrain while reducing blood flow in the motor areas. These findings may explain why taking Ritalin can help hyperactive children coordinate fine and gross motor movements while improving attention. Other research has focused on the thalamus, reticular activating system, and the anterior midbrain bundle. Compared to normal controls, hyperactive children also show differences in neuroendocrine function. Studies have found that the growth hormone response to amphetamines or Ritalin differs in hyperactive children, further highlighting the biological differences between hyperactive and normal children.
bubble_chart Clinical Manifestations
Most children exhibit symptoms from infancy or early childhood, such as being easily excitable, crying frequently, having poor sleep, difficulty feeding, and struggling to establish regular toilet habits. As they grow older, in addition to increased activity, they may show poor coordination, short attention spans or difficulty concentrating, purposeless behavior, impulsive emotions with poor self-control, and challenges in following classroom rules or learning. Although these children have normal intelligence, their ability to learn is often below average due to poor concentration, weak auditory discrimination, and limited language expression. Clinical symptoms are most prominent in school-aged children: they talk excessively in class, fidget frequently, become easily agitated, and often argue with others. Their behavior lacks clear purpose—for example, they may take others' belongings or act recklessly without regard for danger. They struggle to fit in during group activities and may appear stubborn, disobedient, impulsive, or rude in front of their parents. Some children adopt an avoidant attitude toward challenges, becoming passive or withdrawn. As they grow older, many experience learning difficulties, even though their IQ levels are typically normal or near-normal. These symptoms still hinder academic performance. Some children with hyperactivity also exhibit perceptual-motor impairments. For instance, when copying drawings, they may struggle to distinguish between the main subject and background, fail to analyze the composition of shapes, or integrate parts into a whole. Some may misread "6" as "9" or "d" as "b," or even confuse left and right. The former issue relates to difficulties in synthesis and analysis, while the latter involves spatial orientation problems. Additionally, they may face challenges in reading, spelling, writing, or verbal expression. Their tendency to answer without careful thought and incomplete comprehension further contributes to learning difficulties. Moreover, hyperactive children often display certain neurological "soft signs," such as positive results in tests like palm flipping or finger opposition.
【Treatment Measures】Since there is no clear pathological change as a diagnostic basis so far, the current diagnosis still mainly relies on the medical history provided by the child's parents and teachers, clinical manifestations, physical examination (including neurological examination), and mental examination as the primary basis:
1. Symptom Criteria: Compared to most children of the same age, the following symptoms are more common. Eight of the following behaviors must be present.
(1) Often fidgets with hands or feet or squirms in seat. (In older children or adolescents, this may be limited to subjective feelings of restlessness.)
(2) Has difficulty remaining seated when required to do so.
(3) Is easily distracted by external stimuli.
(4) Has difficulty waiting for their turn in games or group activities.
(5) Often blurts out answers before questions have been completed.
(6) Has difficulty following instructions (not due to oppositional behavior or failure to understand), such as failing to complete chores.
(7) Has difficulty sustaining attention in tasks or play activities.
(8) Often shifts from one uncompleted activity to another.
(9) Has difficulty playing quietly.
(10) Often talks excessively.
(11) Often interrupts or intrudes on others' activities, such as disrupting other children's games.
(12) Often does not seem to listen when spoken to directly.
(13) Often loses items necessary for school or home activities (e.g., toys, pencils, books, or homework).
(14) Often engages in physically dangerous activities without considering possible consequences (not for the purpose of seeking thrills).
2. Duration Criteria: Symptoms typically appear before the age of 7 and persist for more than 6 months.
3. Exclusion Criteria: The condition is not caused by pervasive developmental disorders, intellectual disability, childhood psychiatric disorders, organic mental disorders, neuropsychiatric diseases, or adverse drug reactions.
4. Severity Classification:
(1) Grade I: Symptoms meet or slightly exceed the diagnostic criteria, with minimal or no impairment in school or social functioning.
(2) Moderate: Symptoms and impairment fall between Grade I and Grade III.
(3) Grade III: Symptoms far exceed the diagnostic criteria, with significant and widespread impairment in school, family, and peer relationships.
bubble_chart Treatment Measures
1. Drug Therapy Medications for treating this condition can be divided into central nervous system stimulants, antidepressants, antipsychotics, and antiepileptics. However, central nervous system stimulants such as methylphenidate or dextroamphetamine are commonly used. The details are introduced as follows: ① Methylphenidate (Ritalin): Currently a commonly used medication. The dosage is 5–10 mg per dose, taken twice daily in the morning and at noon. It should not be taken in the evening to avoid insomnia. Most children require a daily dose of no more than 20 mg. Since stimulants may affect physical development, it is recommended that children take the medication only during school days and discontinue use on weekends and holidays. It is generally not used in children under 6 years old. This drug has the advantage of being less likely to cause tolerance. ② Dextroamphetamine (Dexedrine): Another commonly used medication, with a dosage of 2.5–5 mg per dose, taken twice daily in the morning and at noon. Most children require a daily dose of no more than 10 mg. Changes in pulse and blood pressure should be monitored. Side effects include insomnia, dizziness, loss of appetite, and weight loss. It is also advisable to discontinue use on Sundays and holidays to reduce its growth-suppressing side effects. It is generally not used in children under 3 years old. Long-term use of this drug has a more pronounced impact on growth and development compared to methylphenidate, but its effects are easier to predict, which is considered an advantage. Additionally, it has some antiepileptic effects, making it more suitable for patients with concurrent seizures. ③ Another stimulant, Pemoline (Cylert): Considered significantly effective for hyperactivity, with a long duration of action—only one dose in the morning before school is needed. It has fewer side effects and is less likely to cause anorexia and insomnia compared to dextroamphetamine and methylphenidate. It is best not used in children under 6 years old. The initial dose is 10 mg, which can be increased to 20–40 mg if the response is unsatisfactory. This drug has a slower onset of action, and if ineffective, it should be discontinued. There have been reports of delayed hypersensitivity reactions affecting the liver, so liver function should be monitored regularly during treatment. ④ Caffeine: Also effective for childhood hyperactivity, with a dosage of 100–150 mg per dose, taken twice daily, though its efficacy is inferior to methylphenidate and dextroamphetamine. ⑤ Imipramine (Tofranil): An antidepressant that is also effective for this condition. The dosage starts at 10 mg, with a usual daily dose of 25–50 mg, adjusted based on the child’s age and weight. The drug-induced leukopenia is often temporary and resolves after discontinuation. A white blood cell count should be checked once after the first 4 weeks of treatment, followed by blood tests every two weeks. Other side effects include loss of appetite, urinary retention, or allergic reactions. It is not suitable for children under 12 years old. ⑥ Antipsychotics: Such as chlorpromazine and thioridazine, are suitable for children with disruptive behaviors. ⑦ Antiepileptics: Such as phenytoin and primidone, are suitable for patients with concurrent seizures. Barbiturate sedatives should be avoided, as they may sometimes worsen symptoms.
The duration of treatment depends on the severity of the condition. Mild cases may require medication for 6 months to 1 year, while severe cases may need treatment for 3–5 years. Discontinuing medication too early may lead to symptom recurrence.
2. Psychotherapy Drug treatment is symptomatic. Hyperactivity is often controlled through medication. At the same time, appropriate education and management from family and school should not be neglected. The attitude toward the child should be handled with patience, care, and affection. For the child’s undesirable behaviors or unlawful actions, positive disciplinary education should be provided, with ample guidance and encouragement. When behavioral therapy shows progress, rewards should be given. Psychological pressure should not be applied, and verbal abuse or corporal punishment must be avoided. For children with bad habits or learning difficulties, more concrete guidance should be provided, along with a structured daily routine to cultivate good habits and help them overcome learning challenges, thereby continuously boosting their confidence. Literature indicates that while medication is effective, combining it with education and behavioral guidance yields even better results.
With the application of various treatment methods, the prognosis for childhood hyperactivity is relatively optimistic. However, if left untreated, approximately one-third of hyperactive children will meet the diagnostic criteria for DSM-III-R Axis I disorders by adulthood. These mainly fall into four categories: ① residual symptoms of hyperactivity, ② antisocial personality disorder, ③ alcohol dependence, and ④ hysteria, anxiety disorders, and some schizophrenia-like conditions. Many adults with personality disorders have a history of childhood hyperactivity, exhibiting poorly controlled impulsive behaviors, low stress tolerance thresholds, emotional instability, and chronic dissatisfaction. Follow-up studies of untreated or minimally treated hyperactive children provide insight into the natural course of the disorder. Some reports indicate that untreated hyperactive children show a reduction in aimless excessive activity as they age. However, 20% of these individuals continue to exhibit criminal behavior, substance abuse, poor academic performance, impulsivity, and attention deficits during adolescence.
There are six main criteria for identifying symptoms similar to ADHD. ① Intellectual disability, ② Autism spectrum disorder, ③ Depression, ④ Chronic social environmental issues, ⑤ Tourette syndrome or multiple tic syndrome, ⑥ Other behavioral disorders.
