Despite the scientifically well-established nature of attention deficit hyperactivity disorder (ADHD), its diagnosis, and its treatment, each of these has been controversial since the 1970s. The controversies involve clinicians, teachers, policymakers, parents, and the media. Positions range from the view that ADHD is within the normal range of behavior to the hypothesis that ADHD is a genetic condition. Other areas of controversy include the use of stimulant medications in children, the method of diagnosis, and the possibility of overdiagnosis. In 2009, the National Institute for Health and Care Excellence, while acknowledging the controversy, stated that the current treatments and methods of diagnosis are based on the dominant view of the academic literature.

With differing rates of diagnosis across countries, states within countries, races, and ethnicities, some suspect factors other than the presence of the symptoms of ADHD are playing a role in diagnosis, although the prevalence of ADHD is consistent internationally. Some sociologists consider ADHD to be an example of the medicalization of deviant behavior, that is, turning the previously issue of school performance into a medical one. Most healthcare providers accept ADHD as a genuine disorder, at least in the small number of people with severe symptoms. Among healthcare providers the debate mainly centers on diagnosis and treatment in the much greater number of people with mild symptoms.

Status as a disorder According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), the leading authority in the US on clinical diagnosis, ADHD is a neurodevelopmental disorder with a prevalence rate in most cultures of about 5% in children and 2.5% in adults. Today, the existence of ADHD is widely accepted, but controversy around the disorder has existed since at least the 1970s. According to the DSM-5, symptoms must be present before age 12, but it is not uncommon for ADHD to continue into adulthood. Parents and educators sometimes still question a perceived over-diagnosis in children due to overlapping symptoms with other mental disabilities, and the effectiveness of treatment options, especially the overprescription of stimulant medications. However, according to sociology professor Vincent Parrillo, "Parent and consumer groups, such as CHADD (Children and Adults with Attention Deficit Hyperactivity Disorder), tend to support the medical perspective of ADHD."

In 2009, the British Psychological Society and the Royal College of Psychiatrists, in collaboration with the National Institute for Health and Care Excellence (NICE), released a set of diagnosis and treatment guidelines for ADHD. These guidelines reviewed studies by Ford et al. that found that 3.6 percent of boys and 0.85 percent of girls in Britain qualified for a diagnosis of ADHD using the American DSM-IV criteria. The guidelines go on to state that the prevalence drops to 1.5% when using the stricter criteria for the ICD-10 diagnosis of hyperkinetic disorder, used mainly in Europe.

A systematic review of the literature in 2007 found that the worldwide prevalence of ADHD was 5.29 percent, and that there were no significant differences in prevalence rates between North America and Europe. The review did find differences between prevalence rates in North America and those in Africa and the Middle East, but cautioned that this may be due to the small number of studies available from those regions.

Causes

The pathogenesis of ADHD is not wholly clear, however a large body of scientific evidence supports that it is caused by a complex mixture of genetic, pre-natal and early post-natal environmental factors.

ADHD as a biological difference Large, high quality research has found small differences in the brain between ADHD and non-ADHD patients. Jonathan Leo and David Cohen, critics who reject the characterization of ADHD as a disorder, contended in 2003 and 2004 that the controls for stimulant medication usage were inadequate in some lobar volumetric studies, which makes it impossible to determine whether ADHD itself or psychotropic medication used to treat ADHD is responsible for decreased thickness observed in certain brain regions. They believe many neuroimaging studies are oversimplified in both popular and scientific discourse and given undue weight despite deficiencies in experimental methodology. Many studies and meta-analyses have demonstrated differences in multiple aspects of brain structure and function.

ADHD is highly heritable: twin studies suggest that genetics explain 70 to 80 percent of the variation of ADHD. There is also strong evidence to support genetic-environment interactions with some fetal and early post-natal environmental factors. However, some have questioned whether a genetic connection exists as no single gene has been found – this is known as the missing heritability problem, which ADHD shares with many other heritable human traits such as schizophrenia. In 2000, Dr. Joseph Glenmullen stated that "no claim of a gene for a psychiatric condition has stood the test of time, in spite of popular misinformation. Although many theories exist, there is no definitive biological, neurological, or genetic etiology for 'mental illness'." Authors of a review of ADHD etiology in 2004 noted: "Although several genome-wide searches have identified chromosomal regions that are predicted to contain genes that contribute to ADHD susceptibility, to date no single gene with a major contribution to ADHD has been identified." However, several large studies and reviews provide strong support that ADHD is polygenic in most cases, caused by a complex interaction between multiple genes – there is no single gene which would cause the majority of ADHD cases.

Social construct theory

Some social constructionist theories of ADHD reject the dominant medical consensus that ADHD has a distinct pathophysiology and genetic components. Many social constructionists trenchantly question deterministic views of behaviour, such as those views sometimes put forth within behavioural/abnormal psychology and the biological sciences. Concerns have been raised over the threshold at which symptoms are pathologized, and how strongly social constructs surrounding the symptoms and diagnosis of ADHD may differ between cultures. The social construction theory of ADHD argues that attention deficit hyperactivity disorder is not necessarily an actual pathology, but that an ADHD diagnosis is a socially constructed explanation to describe behaviors that simply do not meet prescribed social norms.

Some proponents of the social construct theory of ADHD seem to regard the disorder as genuine, though over-diagnosed in some cultures. These proponents cite as evidence that the DSM IV, favored in the United States for defining and diagnosing mental illness, arrives at levels of ADHD three to four times higher than criteria in the ICD 10, the diagnostic guide favored by the World Health Organization. A popular proponent of this theory, Thomas Szasz, has argued that ADHD was "invented and not discovered."

Psychiatrists Peter Breggin and Sami Timimi oppose pathologizing the symptoms of ADHD. Sami Timimi, who is a child and adolescent psychiatrist with the NHS, argues that ADHD is not an objective disorder but that western society creates stress on families which in turn suggests environmental causes for children expressing the symptoms of ADHD. They also believe that parents who feel they have failed in their parenting responsibilities can use the ADHD label to absolve guilt and self-blame. Timimi's view has been heavily criticized by psychiatrist and ADHD expert Russell Barkley, a strong proponent of ADHD as an independent pathology and of medicating children for ADHD symptoms.

A common argument against the medical model of ADHD asserts that, while the traits that define ADHD exist and may be measurable, they lie within the spectrum of normal healthy human behaviour and are not dysfunctional. As Thomas Szasz puts it, everyone has problems and difficulties that should be categorized as "problems of living", not mental illnesses or diseases. However, by definition, in order to diagnose with a mental disorder, symptoms must be interpreted as causing a person distress or be especially maladaptive. In the United States, the Diagnostic and Statistical Manual (DSM-IV) requires that "some impairment from the symptoms is present in two or more settings" and that "there must be clear evidence of significant impairment in social, school, or work functioning" for a diagnosis of ADHD to be made.

In this view, in societies where passivity and order are highly valued, those on the active end of the active-passive spectrum may be seen as problems. Medically defining their behaviour (through medical labels such as ADHD) serves the purpose of removing blame from those causing the problem. However, strict social constructions views are controversial, due to a number of studies that cite significant psychological and social differences between those diagnosed with the disorder, and those who are not. The specific reasons for these differences are not certain, and this does not suggest anything other than a difference in behavior. Studies have also shown neurological differences, but whether this signifies an effect rather than a cause is unknown. Such differences could also be attributed the drugs commonly prescribed to people with this disorder. Studies have also been able to differentiate ADHD from other psychiatric disorders in its symptoms, associated features, life course, and comorbidity.

Gerald Coles, an educational psychologist and formerly an associate professor of clinical psychiatry at Robert Wood Johnson Medical School and the University of Rochester who has written extensively on literacy and learning disabilities, asserts that there are partisan agendas behind the educational policy-makers and that the scientific research that they use to support their arguments regarding the teaching of literacy are flawed. These include the idea that there are neurological explanations for learning disabilities. Gerald Coles argues that school failure must be viewed and treated in the context of both the learning environment and the child's individual abilities, behavior, family life, and social relationships. He then presents a new model of learning problems, in which family and school environments are the major determinants of academic success. In this interactive paradigm, the attitudes and methods of education are more important than inherent strengths or deficits of the individual child.

Diagnosis

Methods of diagnosis Since the early 2000s, research on the functioning of the brain has been conducted to help support the idea that Attention Deficit Hyperactivity Disorder is an executive dysfunction issue. The brains of males and females are showing differences, which could potentially help explain why ADHD presents differently in boys and girls. The current method of diagnosis made is using the DSM-5, along with a possible physical and visual examination.

Over- and under-diagnosis