Attention deficit hyperactivity disorder (ADHD) is a disability and mental disorder of the neurodevelopmental type. It is characterized by problems focusing attention at will, excessive activity, or difficulty controlling behavior which is not appropriate for a person's age.
ADHD is an executive function disability. Executive dysfunction in domains such as response inhibition, planning, vigilance, and working memory plays an important role in the complex neuropsychology of ADHD. Nonetheless, EF weaknesses are neither necessary nor sufficient to cause all cases of ADHD.
The medical literature has described symptoms similar to ADHD since the 19th century.[30] ADHD, its diagnosis, and its treatment have been considered controversial since the 1970s.
In children, ADHD occurs with other disorders about ⅔ of the time.[12] Some commonly associated conditions include learning disabilities; Tourette syndrome; Oppositional Defiant Disorder (ODD); autism; Conduct Disorder (CD); Primary disorder of vigilance; Sluggish Cognitive Tempo (SCT); Sleep Disorders; Mood Disorders; Anxiety Disorders; Substance Use Disorders; Obsessive-compulsive disorder (OCD);
Learning disabilities have been found to occur in about 20–30% of children with ADHD and can include developmental speech and language disorders and academic skills disorders.[50] ADHD, however, is not considered a learning disability, but it very frequently causes academic difficulties.[50]
History[]
Clinical diagnoses of Attention Deficit Hyperactivity Disorder (ADHD) in children, adolescents, and adults have grown remarkably over the last fifty years. Officially recognized in the United States as a medical condition in 1968 by the Diagnostic and Statistical Manual for Mental Disorders (DSM) for the primary symptoms of inattention, hyperactivity, and impulsivity in children, ADHD has gradually spread around the world to reach even underdeveloped nations with equally significant prevalence (Conrad & Singh, 2018; Scheffler et al., 2007). At the same time, diagnostic criteria have been further expanded and specified for adolescents and adults with the acknowledgement that ADHD persists throughout the lifespan (Epstein, 2013). Currently, eighteen core symptoms describe at least forty attention-related behavioral disorders, and dynamic DSM criteria evolve with efforts to categorize the nebulous condition (Epstein, 2013). Globally, ADHD prevalence is estimated at 9.5% for children and adolescents and almost 3% in adults (Doshi et al., 2012; Fayyad et al., 2017).
Until the 1990s, international diagnosis and treatment of ADHD was uncommon. Rapid growth and spread of technology and communication channels, particularly in the healthcare and pharmaceutical industries, introduced Western psychiatry to almost every corner of the globe, contributing to the medicalization of ADHD and other mental health issues (Conrad & Singh, 2018). Estimates for the economic costs of ADHD range from $140 to $260 billion in the US alone, including additional education and medical care for children and loss of productivity and income in adults (Doshi et al., 2012). Adult ADHD is highly comorbid with medical and mental health conditions, generating further individual and public health costs with significant social ramifications (Fayyad et al., 2017). Long-term, individuals with ADHD attain fewer academic achievements, earn lower incomes, and have less-successful relationships (J. R. Galler et al., 2012). [Greenblatt 18]
Co-occurring conditions[]
- Tourette syndrome has been found to occur more commonly in the ADHD population.[1]
- Oppositional defiant disorder (ODD) and conduct disorder (CD), which occur with ADHD in about 50% and 20% of cases respectively.[51] They are characterized by antisocial behaviors such as stubbornness, aggression, frequent temper tantrums, deceitfulness, lying, and stealing.[52] About half of those with hyperactivity and ODD or CD develop antisocial personality disorder in adulthood.[53] Brain imaging supports that conduct disorder and ADHD are separate conditions.[54]
- Primary disorder of vigilance, which is characterized by poor attention and concentration, as well as difficulties staying awake. These children tend to fidget, yawn and stretch and appear to be hyperactive in order to remain alert and active.[55]
- Sluggish cognitive tempo (SCT) is a cluster of symptoms that potentially comprises another attention disorder. It may occur in 30–50% of ADHD cases, regardless of the subtype.[56]
- Mood disorders (especially bipolar disorder and major depressive disorder). Boys diagnosed with the combined ADHD subtype are more likely to have a mood disorder.[57]Adults with ADHD sometimes also have bipolar disorder, which requires careful assessment to accurately diagnose and treat both conditions.[58]
- Anxiety disorders have been found to occur more commonly in the ADHD population.[57]
- Obsessive-compulsive disorder (OCD) can co-occur with ADHD and shares many of its characteristics.[52]
- Substance use disorders. Adolescents and adults with ADHD are at increased risk of substance abuse.[19] This is most commonly seen with alcohol or cannabis.[19] The reason for this may be an altered reward pathway in the brains of ADHD individuals.[19] This makes the evaluation and treatment of ADHD more difficult, with serious substance misuse problems usually treated first due to their greater risks.[59][60]
- Restless legs syndrome has been found to be more common in those with ADHD and is often due to iron deficiency anaemia.[61][62] However, restless legs can simply be a part of ADHD and requires careful assessment to differentiate between the two disorders.[63]
- Sleep disorders and ADHD commonly co-exist. They can also occur as a side effect of medications used to treat ADHD. In children with ADHD, insomnia is the most common sleep disorder with behavioral therapy the preferred treatment.[64][65] Problems with sleep initiation are common among individuals with ADHD but often they will be deep sleepers and have significant difficulty getting up in the morning.[66] Melatonin is sometimes used in children who have sleep onset insomnia.[67]
- People with ADHD have an increased risk of persistent bed wetting.[68]
- A 2016 systematic review found a well established association between ADHD and obesity, asthma and sleep disorders, and tentative evidence for association with celiac disease and migraine,[69] while another 2016 systematic review did not support a clear link between celiac disease and ADHD, and stated that routine screening for celiac disease in people with ADHD is discouraged.[70]