When was ADHD discovered?

The first medical descriptions are older than most people expect

The oldest known clinical account is from 1775. Melchior Adam Weikard, a German physician, included a chapter on lack of attention in a medical textbook, describing people who were easily distracted by any sound, inconstant, careless and unable to persist, and he attributed the problem to the nervous system rather than to bad character. In 1798 the Scottish physician Alexander Crichton published a chapter on attention in which he described a mental restlessness that made sustained attention painful and noted that it was often present from birth and tended to lessen with age. Both descriptions would be recognisable to a clinician today.

The German physician Heinrich Hoffmann's 1845 story of Fidgety Philip, a boy who cannot sit still at dinner, is often cited as an early portrait, though it is a children's rhyme rather than a medical text. What these sources show is that the pattern was observed and written down long before anyone had a name for it, which is one answer to the claim that ADHD is a modern invention.

In 1902 George Still described the pattern clinicians still recognise

The description usually treated as the start of the modern condition came from George Frederic Still, a British paediatrician, in three lectures to the Royal College of Physicians in 1902, later published in The Lancet. Still described a group of children with what he called an abnormal defect of moral control: they were impulsive, inattentive, often defiant and unable to learn from consequences, despite normal intelligence and, in many cases, good upbringing. He argued that the condition was biological, noted that it appeared more often in boys, and observed that it tended to show before the age of eight. Still's account is cited as the first systematic clinical description, and his emphasis on an inherited, biological basis anticipated the next century of research.

Still's language has not aged well. Defect of moral control reflected the vocabulary of his era, and his assumptions about which families produced such children were shaped by class as much as by evidence. What has lasted is the clinical core: a group of children with normal intelligence who could not sustain attention or inhibit impulses, whose difficulties began early and persisted, and whose behaviour was not explained by how they were raised. That description, stripped of its moral framing, is close to the inattentive and impulsive symptom lists used today.

The twentieth century turned a description into a recognised, treatable condition

Between Still's lectures and the first official diagnosis in 1968, the understanding of ADHD developed in steps, each adding a piece of the modern picture.

• 1917 to 1928. After the encephalitis lethargica epidemic, physicians described children left with hyperactivity, impulsivity and attention problems, which supported the idea that the pattern had a brain basis.
• 1937. The American physician Charles Bradley reported that a stimulant medication given to children in a residential hospital improved their behaviour and schoolwork, the first observation of a treatment effect that research later confirmed.
• 1950s. The term hyperkinetic impulse disorder entered use, placing hyperactivity at the centre of the condition.
• 1960s. The label minimal brain dysfunction was widely applied, reflecting the belief that subtle brain injury was responsible; the label was later abandoned because no such injury could be found in most cases.
• 1968 and 1972. The DSM-II listed hyperkinetic reaction of childhood, and Canadian psychologist Virginia Douglas's research at McGill shifted attention from overactivity to sustained attention and impulse control, which shaped the 1980 criteria.

The sequence of official names and criteria from 1968 onward, including how the diagnosis reached adults, is set out in when did ADHD become a diagnosis?

Adult ADHD and its biology were recognised much later, from the 1970s to the 1990s

For most of the twentieth century ADHD was assumed to be a childhood condition that faded in adolescence. Studies in the 1970s that followed children into adulthood, and early clinical work on adults with persistent symptoms, showed that this was wrong for a large share of people. Through the 1980s and 1990s, twin and family studies established that ADHD is among the most heritable psychiatric conditions, and the first brain imaging studies found differences in activity and structure in regions involved in attention and self-regulation. Adult ADHD reached the general public in the mid-1990s, and the diagnostic manuals finally wrote adult criteria in 2013.

Canada played a part in this shift. Virginia Douglas's research group at McGill in the 1970s reframed the condition around sustained attention and impulse control, and Canadian clinicians were among the early contributors to adult ADHD research and to the practice guidelines that CADDRA now maintains.

The science continues. No scan or genetic test can diagnose an individual, as discussed in what role, if any, do brain scans and EEG have in an ADHD assessment?, but the accumulated evidence from genetics, imaging, neuropsychology and long-term outcome studies is why every major medical body treats ADHD as a valid neurodevelopmental condition.

The timeline matters because it answers the people who say ADHD is not real

Adults being assessed today often hear from family or colleagues that ADHD is a recent fashion. The record says otherwise: physicians described the pattern in the 1770s, defined it clinically in 1902, found a treatment response in 1937, and have studied its biology for fifty years. What is recent is the recognition that the condition persists into adulthood and that inattentive presentations, which are common in girls and women, were missed for generations. That recognition is why so many Canadians are being assessed for the first time in their thirties, forties and beyond.