Neurodevelopmental disorder
Attention deficit hyperactivity disorder |
Other names |
Formerly: Attention deficit disorder (ADD), hyperkinetic disorder (HD)[1] |
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ADHD arises from maldevelopment in brain regions such as the prefrontal cortex, basal ganglia and anterior cingulate cortex, which regulate the executive functions necessary for human self-regulation. |
Specialty |
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Symptoms |
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Usual onset |
Prior to age 12 |
Causes |
Genetic (inherited, de novo) and to a lesser extent, environmental factors (exposure to biohazards during pregnancy, traumatic brain injury) |
Diagnostic method |
Based on impairing symptoms after other possible causes have been ruled out |
Differential diagnosis |
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Treatment |
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Medication |
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Frequency |
0.8–1.5% (2019, using DSM-IV-TR and ICD-10)[3] |
Attention deficit hyperactivity disorder (ADHD)[1] is a neurodevelopmental disorder characterized by symptoms of inattention, hyperactivity, impulsivity, and emotional dysregulation that are excessive and pervasive, impairing in multiple contexts, and developmentally inappropriate.[9] ADHD symptoms arise from executive dysfunction.[18]
Impairments resulting from deficits in self-regulation such as time management, inhibition, task initiation, and sustained attention[19] can include poor professional performance, relationship difficulties, and numerous health risks,[20][21] collectively predisposing to a diminished quality of life[22] and a reduction in life expectancy.[23][24] It is associated with other mental disorders as well as non-psychiatric disorders, which can cause additional impairment.[8] The disorder costs society hundreds of billions of US dollars each year, worldwide.[25]
While people with ADHD often struggle to initiate work and persist on tasks with delayed consequences, this may not be evident in contexts they find intrinsically interesting and immediately rewarding,[17][26] a symptom colloquially known as hyperfocus.[27] This mental state is often hard to disengage from[28][29] and is related to risks such as for internet addiction.[30]
ADHD can be difficult to tell apart from other conditions.[16][22] It represents the extreme lower end of the continuous dimensional trait (bell curve) of executive functioning and self-regulation, which is supported by twin, brain imaging and molecular genetic studies.[37]
The precise causes of ADHD are unknown in most individual cases.[38][39] Meta-analyses have shown that the disorder is primarily genetic with a heritability rate of 70-80%,[40] where risk factors are highly accumulative.[41] The environmental risks are not related to social or familial factors;[42][43][44] they exert their effects very early in life, in the prenatal or early postnatal period.[8] However, in rare cases, ADHD can be caused by a single event including traumatic brain injury,[40][45][46][47] exposure to biohazards during pregnancy,[8] or a major genetic mutation.[48] As it is a neurodevelopmental disorder, there is no biologically distinct adult-onset ADHD except for when ADHD occurs after traumatic brain injury.[8][49]