attention deficit hyperactivity disorder

attention deficit hyperactivity disorder
Name	Attention deficit hyperactivity disorder
Synonyms	Hyperkinetic disorder (ICD-10)
Field	Psychiatry, Pediatrics
Symptoms	Inattention, hyperactivity, impulsivity
Complications	Academic underachievement, Substance use disorder, Mood disorder
Onset	Childhood
Duration	Often lifelong
Types	Predominantly inattentive, predominantly hyperactive-impulsive, combined
Causes	Genetic and environmental factors
Risks	Premature birth, Low birth weight, Prenatal exposure to tobacco
Diagnosis	Based on symptoms after other possible causes excluded
Differential	Anxiety disorder, Bipolar disorder, Autism spectrum disorder, Hearing loss
Treatment	Behavior therapy, Stimulant medication, Cognitive behavioral therapy
Medication	Methylphenidate, Amphetamine, Atomoxetine
Prognosis	Variable; symptoms often persist into adulthood
Frequency	~5–7% of children, ~2–5% of adults (global)

attention deficit hyperactivity disorder. It is a neurodevelopmental disorder characterized by persistent patterns of inattention, hyperactivity, and impulsivity that interfere with functioning or development. The condition is typically first diagnosed in childhood and often continues into adulthood, affecting academic, occupational, and social performance. Its presentation is heterogeneous, and it is frequently comorbid with other mental health conditions.

Signs and symptoms

Core symptoms are categorized into inattention and hyperactivity-impulsivity, as defined in the Diagnostic and Statistical Manual of Mental Disorders. Inattentive behaviors may include careless mistakes, difficulty sustaining focus, and being easily distracted, often leading to problems in settings like school or the workplace. Hyperactive-impulsive behaviors manifest as excessive fidgeting, an inability to remain seated, and intrusive actions such as interrupting others. These symptoms must be inconsistent with developmental level and cause significant impairment in multiple settings, such as at home and in social situations with peers. Many individuals also experience associated difficulties like emotional dysregulation, executive dysfunction, and rejection sensitive dysphoria.

Causes

The etiology is complex and involves a strong genetic component, with heritability estimated around 70-80%. Numerous candidate genes related to dopamine and norepinephrine neurotransmission, such as those encoding the dopamine transporter and dopamine receptor D4, have been implicated. Non-inherited risk factors include environmental exposures like prenatal exposure to tobacco or alcohol, premature birth, and low birth weight. Neuroanatomically, studies using magnetic resonance imaging have noted subtle differences in brain structure, particularly in the prefrontal cortex, basal ganglia, and cerebellum. There is no scientific evidence supporting links to factors like vaccination or excessive sugar consumption.

Diagnosis

Diagnosis is clinical and based on criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders or the International Classification of Diseases. There is no single biological test; assessment involves gathering information from multiple sources, including parents, teachers, and direct observation. Standardized rating scales, such as the Conners' Rating Scales, are commonly used tools. Clinicians must rule out other conditions that can mimic its symptoms, including anxiety disorder, bipolar disorder, autism spectrum disorder, hearing loss, and sleep disorder. A comprehensive evaluation is essential, as symptoms must be present before age 12 and cause significant impairment in social, academic, or occupational functioning.

Management

Management strategies are multimodal and tailored to the individual. The most effective treatment for children often combines behavior therapy and medication. First-line pharmacological treatments typically include stimulant medications like methylphenidate (e.g., Ritalin) and amphetamine (e.g., Adderall). Non-stimulant options include atomoxetine and guanfacine. For adults, cognitive behavioral therapy adapted for the condition is a cornerstone of treatment. Accommodations in educational settings, such as those outlined in an Individualized Education Program in the United States, are also critical. Ongoing monitoring by healthcare professionals like psychiatrists or pediatricians is necessary to adjust treatment plans.

Prognosis

While some children may see a reduction in hyperactive-impulsive symptoms with age, many experience persistent core deficits into adolescence and adulthood. Long-term outcomes vary widely and are influenced by factors such as the presence of comorbid conditions, family support, and access to effective treatment. Adults with the disorder are at increased risk for substance use disorder, mood disorder, anxiety disorder, and difficulties with employment and relationships. However, with appropriate management, many individuals develop successful coping strategies and lead productive lives, with some evidence suggesting associations with traits like creativity and entrepreneurial drive.

Epidemiology

It is one of the most common neurodevelopmental disorders. Global prevalence in children and adolescents is estimated at approximately 5–7%, though figures vary by diagnostic criteria and region. In the United States, data from the Centers for Disease Control and Prevention indicate a diagnosed prevalence of around 9.8% among children aged 3-17. It is diagnosed more frequently in males than females in childhood, but this gender gap narrows in adulthood. Prevalence studies in adults suggest a rate of 2–5% worldwide. Diagnosis rates have increased over recent decades, a trend attributed to greater awareness, changes in diagnostic practices, and possibly broader environmental factors.

History

Descriptions of symptoms consistent with the disorder appear in medical literature as early as the 18th century. Sir George Still is often credited with giving a series of lectures in 1902 to the Royal College of Physicians describing children with deficits in "moral control." Throughout the mid-20th century, the condition was often referred to as "minimal brain dysfunction." The term "hyperkinetic reaction of childhood" was introduced in the DSM-II in 1968. The modern name and diagnostic criteria were established in the DSM-III in 1980, with significant revisions in subsequent editions like the DSM-5. The work of researchers like Virginia Douglas and Paul Wender was instrumental in shaping the contemporary understanding of the disorder's cognitive and adult manifestations.

Category:Neurodevelopmental disorders Category:Mental and behavioural disorders