What is ADHD?
Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder characterized by persistent patterns of inattention, hyperactivity, and impulsivity that interfere with functioning or development across multiple settings. 1
Diagnostic Criteria
According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), ADHD diagnosis requires:
- An ongoing pattern of inattentive and/or hyperactive-impulsive symptoms lasting at least 6 months
- Multiple symptoms (5 or more for adults; 6 or more for children under 17)
- Symptom onset before age 12
- Symptoms present in two or more settings (e.g., home, school, work)
- Evidence that symptoms interfere with or reduce quality of functioning
- Symptoms not better explained by another mental disorder 1
Core Symptom Domains
Inattentive Symptoms
- Poor attention to detail
- Difficulty sustaining attention on tasks
- Appears preoccupied when spoken to directly
- Difficulty completing tasks (gets distracted)
- Organizational challenges
- Avoids tasks requiring sustained mental effort
- Loses necessary items
- Easily distracted
- Frequently forgetful 1
Hyperactive-Impulsive Symptoms
- Fidgeting or tapping
- Difficulty remaining seated
- Feelings of restlessness
- Loud or disruptive behavior
- Constantly "on the go"
- Excessive talking
- Blurting out answers/interrupting others
- Impatience
- Intrudes on others' activities 1
ADHD Subtypes
Based on symptom presentation, ADHD is classified into three subtypes:
- Predominantly Inattentive Type: 5+ symptoms of inattention but fewer than 5 symptoms of hyperactivity-impulsivity
- Predominantly Hyperactive-Impulsive Type: 5+ symptoms of hyperactivity-impulsivity but fewer than 5 symptoms of inattention
- Combined Type: 5+ symptoms in both categories 1
Epidemiology and Course
ADHD is one of the most common neurodevelopmental disorders in childhood, affecting approximately 8% of children and youth 1. While traditionally considered a childhood disorder, ADHD frequently persists into adulthood, with 14.6% of U.S. adults meeting diagnostic criteria 2.
Adults with ADHD are more likely to present with predominantly inattentive symptoms compared to children 1. The disorder has significant impacts on morbidity, mortality, and quality of life across the lifespan if left untreated 1.
Comorbidities
The majority of individuals with ADHD also meet diagnostic criteria for other mental disorders. Common comorbidities include:
- Emotional/behavioral conditions: anxiety, depression, oppositional defiant disorder, conduct disorders, substance use disorders
- Developmental conditions: learning disabilities, language disorders, autism spectrum disorders
- Physical conditions: tic disorders, sleep disorders 1
Screening for these comorbid conditions is essential as they may alter treatment approaches and affect outcomes 1.
Etiology
While the specific etiology of ADHD remains unknown, strong evidence points to:
- Neurobiological factors: Differences in brain structure and function
- Genetic factors: High heritability (multiple genes involved)
- Environmental factors: Prenatal exposures, early adversity 3
Treatment Approach
ADHD is considered a chronic condition requiring ongoing management. Treatment typically includes:
Pharmacological interventions: Stimulants (methylphenidate, amphetamines) are first-line medications, with non-stimulants (atomoxetine, viloxazine, bupropion) as alternatives 4, 5
Behavioral interventions: Parent training, school accommodations, cognitive-behavioral therapy 6
Educational support: Appropriate educational placement and accommodations 1
Treatment approaches vary by region, with Western guidelines typically recommending medication as first-line treatment, while some Asian guidelines prioritize behavioral and educational interventions before medication 1.
Key Clinical Considerations
- ADHD is not solely a disorder of childhood but often persists throughout the lifespan
- Diagnosis requires comprehensive assessment, not just symptom checklists
- ADHD should be managed as a chronic condition following principles of the medical home model 1
- Treatment must be tailored based on symptom severity, comorbidities, and functional impairment
- Regular monitoring for treatment efficacy and side effects is essential
ADHD significantly impacts quality of life, academic/occupational functioning, and social relationships when inadequately treated, making proper diagnosis and comprehensive management crucial for optimal outcomes.