Attention deficit hyperactivity disorder (ADHD) is a mental disorder of the neurodevelopmental type. It is characterized by problems paying attention, excessive activity, or difficulty controlling behavior which is not appropriate for a person’s age. The symptoms appear before a person is twelve years old, are present for more than six months, and cause problems in at least two settings (such as school, home, or recreational activities). In children, problems paying attention may result in poor school performance. Additionally there is an association with other mental disorders and substance misuse. Although it causes impairment, particularly in modern society, many children with ADHD have a good attention span for tasks they find interesting.
Despite being the most commonly studied and diagnosed mental disorder in children and adolescents, the exact cause is unknown in the majority of cases. It affects about 5–7% of children when diagnosed via the DSM-IV criteria and 1–2% when diagnosed via the ICD-10 criteria. As of 2015 it is estimated to affect about 51.1 million people globally. Rates are similar between countries and depend mostly on how it is diagnosed. ADHD is diagnosed approximately two times more often in boys than in girls, although the disorder is often overlooked in girls because their symptoms differ from those of boys. About 30–50% of people diagnosed in childhood continue to have symptoms into adulthood and between 2–5% of adults have the condition. In adults inner restlessness rather than hyperactivity may occur. The condition can be difficult to tell apart from other conditions, as well as to distinguish from high levels of activity that are still within the range of normative behaviors.
ADHD management recommendations vary by country and usually involve some combination of counseling, lifestyle changes, and medications. The British guideline only recommends medications as a first-line treatment in children who have severe symptoms and for medication to be considered in those with moderate symptoms who either refuse or fail to improve with counseling, though for adults medications are a first-line treatment. Canadian and American guidelines recommend that medications and behavioral therapy be used together as a first-line therapy, except in preschool-aged children. Stimulant medication therapy is not recommended as a first-line therapy in preschool-aged children in either guideline. Treatment with stimulants is effective for at least 14 months; however, their long term effectiveness is unclear. Adults often develop coping skills which make up for some or all of their impairments.
The medical literature has described symptoms similar to those of ADHD since the 18th century. ADHD, its diagnosis, and its treatment have been considered controversial since the 1970s. The controversies have involved clinicians, teachers, policymakers, parents, and the media. Topics include ADHD’s causes and the use of stimulant medications in its treatment.Most healthcare providers accept ADHD as a genuine disorder in children and adults, and the debate in the scientific community mainly centers on how it is diagnosed and treated. The condition was officially known as attention-deficit disorder (ADD) from 1980 to 1987, while before this it was known as hyperkinetic reaction of childhood.
Inattention, hyperactivity (restlessness in adults), disruptive behavior, and impulsivity are common in ADHD.Academic difficulties are frequent as are problems with relationships. The symptoms can be difficult to define, as it is hard to draw a line at where normal levels of inattention, hyperactivity, and impulsivity end and significant levels requiring interventions begin.
According to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), symptoms must be present for six months or more to a degree that is much greater than others of the same age and they must cause significant problems functioning in at least two settings (e.g., social, school/work, or home). The criteria must have been met prior to age twelve in order to receive a diagnosis of ADHD. This requires more than 5 symptoms of inattention or hyperactivity/impulsivity for those under 17 and more than 4 for those over 16 years old.
- Be easily distracted, miss details, forget things, and frequently switch from one activity to another
- Have difficulty maintaining focus on one task
- Become bored with a task after only a few minutes, unless doing something they find enjoyable
- Have difficulty focusing attention on organizing or completing a task
- Have trouble completing or turning in homework assignments, often losing things (e.g., pencils, toys, assignments) needed to complete tasks or activities
- Appear not to be listening when spoken to
- Daydream, become easily confused, and move slowly
- Have difficulty processing information as quickly and accurately as others
- Struggle to follow instructions
- Have trouble understanding details; overlooks details
A person with ADHD hyperactive-impulsive type has most or all of the following symptoms, excluding situations where these symptoms are better explained by another psychiatric or medical condition:
- Fidget or squirm a great deal
- Talk nonstop
- Dash around, touching or playing with anything and everything in sight
- Have trouble sitting still during dinner, school, and while doing homework
- Be constantly in motion
- Have difficulty performing quiet tasks or activities
- Be impatient
- Blurt out inappropriate comments, show their emotions without restraint, and act without regard for consequences
- Have difficulty waiting for things they want or waiting their turn in games
- Often interrupt conversations or others’ activities
Girls with ADHD tend to display fewer hyperactivity and impulsivity symptoms but more symptoms pertaining to inattention and distractability. Symptoms of hyperactivity tend to go away with age and turn into “inner restlessness” in teens and adults with ADHD.
People with ADHD of all ages are more likely to have problems with social skills, such as social interaction and forming and maintaining friendships. This is true for all subtypes. About half of children and adolescents with ADHD experience social rejection by their peers compared to 10–15% of non-ADHD children and adolescents. People with attention deficits are prone to having difficulty processing verbal and nonverbal language which can negatively affect social interaction. They also may drift off during conversations, miss social cues, and have trouble learning social skills.
Difficulties managing anger are more common in children with ADHD as are poor handwriting and delays in speech, language and motor development. Although it causes significant difficulty, many children with ADHD have an attention span equal to or better than that of other children for tasks and subjects they find interesting.
In children, ADHD occurs with other disorders about two-thirds of the time. Some commonly associated conditions include:
- Tourette’s syndrome
- Autism spectrum disorder (ASD): this disorder affects social skills, ability to communicate, behaviour, and interests.
- Anxiety disorders have been found to occur more commonly in the ADHD population.
- Intermittent explosive disorder
- Learning disabilities have been found to occur in about 20–30% of children with ADHD. Learning disabilities can include developmental speech and language disorders and academic skills disorders. ADHD, however, is not considered a learning disability, but it very frequently causes academic difficulties.
- Obsessive–compulsive disorder (OCD) can co-occur with ADHD and shares many of its characteristics.
- Intellectual disabilities
- Reactive attachment disorder
- Substance use disorders. Adolescents and adults with ADHD are at increased risk of substance abuse. This is most commonly seen with alcohol or cannabis. The reason for this may be an altered reward pathway in the brains of ADHD individuals. This makes the evaluation and treatment of ADHD more difficult, with serious substance misuse problems usually treated first due to their greater risks.
- 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. 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. Melatonin is sometimes used in children who have sleep onset insomnia.
- Oppositional defiant disorder (ODD) and conduct disorder (CD), which occur with ADHD in about 50% and 20% of cases respectively. They are characterized by antisocial behaviors such as stubbornness, aggression, frequent temper tantrums, deceitfulness, lying, and stealing. About half of those with hyperactivity and ODD or CD develop antisocial personality disorder in adulthood. Brain imaging supports that conduct disorder and ADHD are separate conditions.
- 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.
- 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.
- Stereotypic movement disorder
- Mood disorders (especially bipolar disorder and major depressive disorder). Boys diagnosed with the combined ADHD subtype are more likely to have a mood disorder.Adults with ADHD sometimes also have bipolar disorder, which requires careful assessment to accurately diagnose and treat both conditions.
- Restless legs syndrome has been found to be more common in those with ADHD and is often due to iron deficiency anemia. However, restless legs can simply be a part of ADHD and requires careful assessment to differentiate between the two disorders.
- People with ADHD have an increased risk of persistent bed wetting.
- 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, 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.