Attention deficit hyperactivity disorder
Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by executive dysfunction occasioning symptoms of inattention, hyperactivity, impulsivity and emotional dysregulation that are excessive and pervasive, impairing in multiple contexts, and otherwise age-inappropriate.[8]
"Attention Deficit" redirects here. For the album, see Attention Deficit (album). For other uses, see Attention deficit (disambiguation).Attention deficit hyperactivity disorder
- Inattention
- carelessness
- hyperactivity
- executive dysfunction
- disinhibition
- emotional dysregulation
- impulsivity
- impaired working memory
Typically at least some ADHD symptoms and impairments onset during the developmental period. Exceptions include if they were compensated for (e.g., by a high IQ or structured environment) or if the individual clearly suffered a neurologically compromising event.
Genetic (inherited, de novo) and to a lesser extent, environmental factors (exposure to biohazards during pregnancy, traumatic brain injury)
Based on symptoms after other possible causes have been ruled out
- Individual without ADHD
- symptomatic but unimpaired
- bipolar disorder
- cognitive disengagement syndrome
- conduct disorder
- major depressive disorder
- autism spectrum disorder
- oppositional defiant disorder
- learning disorder
- intellectual disability
- anxiety disorder[1]
- borderline personality disorder
- fetal alcohol spectrum disorder
- Psychotherapy
- lifestyle changes
- medication
- CNS stimulants (methylphenidate, amphetamine)
- non-stimulants (atomoxetine, viloxazine)
- alpha-2a agonists (guanfacine XR, clonidine XR)
0.8–1.5% (2019, using DSM-IV-TR and ICD-10)[2]
ADHD symptoms arise from executive dysfunction,[17] and emotional dysregulation is often considered a core symptom.[21] Difficulties with self-regulation such as time management, inhibition and sustained attention may result in poor professional performance, relationship difficulties and numerous health risks,[22][23] collectively predisposing to a diminished quality of life[24] and a direct average reduction in life expectancy of 13 years.[25][26] ADHD is associated with other neurodevelopmental and mental disorders as well as some non-psychiatric disorders, which can cause additional impairment, especially in modern society.[27]
Although people with ADHD struggle to persist on tasks with temporally delayed consequences, they may be able to maintain an unusually prolonged level of attention for tasks they do find intrinsically interesting or immediately rewarding;[28][16] this is known as hyperfocus (more colloquially)[29] or perseverative responding.[30] This is a mental state in which a person is completely absorbed in a task to the point of apparently ignoring or "tuning out" everything else, often with difficulty disengaging[28][31] and can be related to risks such as for internet addiction[32] and types of offending behaviour.[33]
ADHD 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.[34][12][35][16][36][37][38]
The precise causes of ADHD are unknown in the majority of cases.[39][40] For most people with ADHD, many genetic and environmental risk factors accumulate to cause the disorder.[41] The environmental risks for ADHD are biological and most often exert their effects in the prenatal period.[7] However, in rare cases a single event might cause ADHD such as traumatic brain injury,[42][43][44][45] exposure to biohazards during pregnancy,[7] a major genetic mutation[46] or extreme environmental deprivation very early in life.[7] There is no biologically distinct adult onset ADHD except for when ADHD occurs after traumatic brain injury.[47][43][7]
Prognosis
ADHD persists into adulthood in about 30–50% of cases.[307] Those affected are likely to develop coping mechanisms as they mature, thus compensating to some extent for their previous symptoms.[220] Children with ADHD have a higher risk of unintentional injuries.[250] Effects of medication on functional impairment and quality of life (e.g. reduced risk of accidents) have been found across multiple domains.[308] Rates of smoking among those with ADHD are higher than in the general population at about 40%.[309]
It affects about 5–7% of children when diagnosed via the DSM-IV criteria,[310] and 1–2% when diagnosed via the ICD-10 criteria.[311] Rates are similar between countries and differences in rates depend mostly on how it is diagnosed.[312] ADHD is diagnosed approximately twice as often in boys as in girls,[4][310] and 1.6 times more often in men than in women,[4] although the disorder is overlooked in girls or diagnosed in later life because their symptoms sometimes differ from diagnostic criteria.[316] About 30–50% of people diagnosed in childhood continue to have ADHD in adulthood, with 2.58% of adults estimated to have ADHD which began in childhood.[218][317] In adults, hyperactivity is usually replaced by inner restlessness, and adults often develop coping skills to compensate for their impairments. The condition can be difficult to tell apart from other conditions, as well as from high levels of activity within the range of normal behaviour. ADHD has a negative impact on patient health-related quality of life that may be further exacerbated by, or may increase the risk of, other psychiatric conditions such as anxiety and depression.[230]
Individuals with ADHD are significantly overrepresented in prison populations. Although there is no generally accepted estimate of ADHD prevalence among inmates, a 2015 meta-analysis estimated a prevalence of 25.5%, and a larger 2018 meta-analysis estimated the frequency to be 26.2%.[318] ADHD is more common among longer-term inmates; a 2010 study at Norrtälje Prison, a high-security prison in Sweden, found an estimated ADHD prevalence of 40%.[319]
Research directions
Possible positive traits
Possible positive traits of ADHD are a new avenue of research, and therefore limited.
A 2020 review found that creativity may be associated with ADHD symptoms, particularly divergent thinking and quantity of creative achievements, but not with the disorder of ADHD itself – i.e. it has not been found to be increased in people diagnosed with the disorder, only in people with subclinical symptoms or those that possess traits associated with the disorder. Divergent thinking is the ability to produce creative solutions which differ significantly from each other and consider the issue from multiple perspectives. Those with ADHD symptoms could be advantaged in this form of creativity as they tend to have diffuse attention, allowing rapid switching between aspects of the task under consideration; flexible associative memory, allowing them to remember and use more distantly-related ideas which is associated with creativity; and impulsivity, which causes people with ADHD symptoms to consider ideas which others may not have. However, people with ADHD may struggle with convergent thinking, which is a cognitive process through which a set of obviously relevant knowledge is utilised in a focused effort to arrive at a single perceived best solution to a problem.[359]
A 2019 article suggested that historical documentation supported Leonardo da Vinci's difficulties with procrastination and time management as characteristic of ADHD and that he was constantly on the go, but often jumping from task to task.[360]
Possible biomarkers for diagnosis
Reviews of ADHD biomarkers have noted that platelet monoamine oxidase expression, urinary norepinephrine, urinary MHPG, and urinary phenethylamine levels consistently differ between ADHD individuals and non-ADHD controls. These measurements could potentially serve as diagnostic biomarkers for ADHD, but more research is needed to establish their diagnostic utility. Urinary and blood plasma phenethylamine concentrations are lower in ADHD individuals relative to controls and the two most commonly prescribed drugs for ADHD, amphetamine and methylphenidate, increase phenethylamine biosynthesis in treatment-responsive individuals with ADHD.[154] Lower urinary phenethylamine concentrations are also associated with symptoms of inattentiveness in ADHD individuals.[361]