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What is ADHD?
Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder characterized by persistent patterns of inattention, hyperactivity, and impulsivity that interfere with daily functioning or development. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) defines ADHD as a condition with symptoms present before age 12, occurring in two or more settings (e.g., home, school), and causing significant social, academic, or occupational impairment (American Psychiatric Association, 2013). The ICD-11 classifies ADHD under “Hyperkinetic Disorder,” emphasizing similar core symptoms (World Health Organization, 2022).
Symptoms of ADHD
DSM-5 criteria divide symptoms into two categories:
- Inattention (≥6 symptoms for children; ≥5 for adults):
- Difficulty sustaining attention in tasks or play.
- Frequent careless mistakes.
- Avoidance of tasks requiring sustained mental effort.
- Easily distracted by extraneous stimuli.
- Forgetfulness in daily activities (e.g., missing appointments).
- Losing items necessary for tasks (e.g., school materials).
- Hyperactivity-Impulsivity (≥6 symptoms for children; ≥5 for adults):
- Fidgeting or tapping hands/feet.
- Inability to stay seated in appropriate situations.
- Excessive running or climbing (in children).
- Inability to engage quietly in leisure activities.
- Interrupting others or blurting out answers.
- Difficulty waiting for turns.
Symptoms must persist for ≥6 months and be inconsistent with developmental level (DSM-5; Kaplan & Sadock’s Synopsis of Psychiatry).
Types of ADHD
The DSM-5 recognizes three ADHD presentations:

- Predominantly Inattentive Presentation: Focused on attention deficits.
- Predominantly Hyperactive-Impulsive Presentation: Dominated by hyperactivity/impulsivity.
- Combined Presentation: Meets criteria for both inattention and hyperactivity-impulsivity.
Note: The ICD-11 uses “Hyperkinetic Disorder” but aligns closely with DSM-5 criteria (Oxford Textbook of Psychiatry).
Causes of ADHD
ADHD arises from a mix of genetic, neurobiological, and environmental factors:
- Neurobiological: Dysregulation of dopamine and norepinephrine pathways; reduced prefrontal cortex and basal ganglia volume (Maudsley Guidelines).
- Genetic: Heritability estimates of 70–80%; associations with genes like DRD4 and DAT1 (Kaplan & Sadock).
- Environmental: Prenatal exposure to toxins (e.g., alcohol, tobacco), low birth weight, and psychosocial adversity (e.g., neglect) (ICD-11).
Diagnosing ADHD
Diagnosis involves:
- Clinical Interviews: Assess symptom history, onset, and functional impact across settings (DSM-5).
- Behavioral Rating Scales: ADHD Rating Scale-5 (ADHD-RS-5) or Conners’ Parent/Teacher Rating Scales.
- Medical Evaluation: Rule out conditions like thyroid disorders, sleep apnea, or hearing deficits.
- Differential Diagnosis: Distinguish from anxiety, learning disabilities, or bipolar disorder (NICE Guidelines).
For adults: Retrospective reporting of childhood symptoms and evidence of impairment in adulthood (e.g., work, relationships).
Treatment for ADHD
Evidence-based interventions include:
- Pharmacotherapy:
- Stimulants: First-line treatments (e.g., methylphenidate, amphetamines) enhance dopamine/norepinephrine activity.
- Non-Stimulants: Atomoxetine (SNRI) or guanfacine (alpha-2 agonist) for non-responders or comorbid anxiety.
- Behavioral Therapies:
- Parent Training in Behavior Management (PTBM): For children with disruptive behaviors.
- Cognitive Behavioral Therapy (CBT): Adults learn organizational skills and emotional regulation.
- School/Workplace Accommodations: Extended time for tasks, structured routines, and environmental modifications.
- Lifestyle Adjustments: Regular exercise, mindfulness practices, and balanced nutrition to support focus (Maudsley Prescribing Guidelines; AACAP Practice Parameters).
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