Attention Deficit Hyperactivity Disorder (ADHD)

Overview

• ADHD is a neurodevelopmental disorder characterized by inattention, hyperactivity, impulsivity, and emotional dysregulation.
• Symptoms arise from executive dysfunction, affecting areas such as time management, inhibition, task initiation, and sustained attention.
• ADHD costs society billions annually and is associated with diminished quality of life and reduced life expectancy.
• Prevalence is estimated at 0.8-1.5% (2019 data).

Causes and Risk Factors

• Genetic Factors: Heritability rate of 70-80%.
• Environmental Factors: Lesser extent, including prenatal exposure to biohazards and traumatic brain injury.
• Precise causes are often unknown; however, genetic mutations and brain injuries are noted causes.

Symptoms

• Inattention: Includes difficulty sustaining focus, disorganization, forgetfulness, and distraction.
• Hyperactivity-Impulsivity: Characterized by excessive fidgeting, inability to stay still, excessive talking, and impulsivity.
• Symptoms must be present in multiple settings and interfere with functioning.
• Girls and women may show more inattention and less hyperactivity.

Diagnosis

• Based on DSM-5 criteria: symptoms must be present for at least six months in two or more settings.
• Diagnosis is often subjective, relying on standardized rating scales and feedback from multiple informants.
• Imaging studies are primarily for research, not diagnostic purposes.

Presentations

• Predominantly Inattentive (ADHD-PI)
• Predominantly Hyperactive-Impulsive (ADHD-PH)
• Combined Presentation (ADHD-C)

Comorbidities

• Common comorbidities include autism spectrum disorder, learning disabilities, mood disorders, anxiety, and substance use disorders.
• Sleep disorders are frequently seen in ADHD patients.

Treatment Options

• Medications: Stimulants (methylphenidate, amphetamine), norepinephrine reuptake inhibitors (atomoxetine), and 2A-adrenergic receptor agonists.
• Behavioral Therapies: First-line treatment for mild symptoms, includes behavior therapy, cognitive behavioral therapy, and parent training.
• Digital Interventions: Emerging tools like game-based therapies (e.g., AKL-T01).

Pathophysiology

• Impairments in neurotransmitter systems, especially dopamine and norepinephrine.
• Brain structural differences, such as reduced volume in specific areas (e.g., prefrontal cortex).

Prognosis

• Many children outgrow symptoms, but 30-50% continue to have symptoms into adulthood.
• ADHD is associated with significant life challenges, such as poor educational outcomes and higher risk of accidents.

Epidemiology

• ADHD affects 6-7% of children and 2.5% of adults globally.
• Higher prevalence in boys than girls, possibly due to differences in symptom presentation and diagnosis.