GP Dr David Turner considers whether we are overdiagnosing adults and children with ADHD
The symptoms of ADHD were identified as far back as 1798. Sir Alexander Crichton, a Scottish doctor, noticed some people were easily distracted and unable to focus on their activities in the way others could.
What is now called ADHD first appeared in 1968 in the DSM-2 – the second edition of the US Diagnostic and Statistical Manual of Mental Disorders. The publication of the DSM-3 in 1980 expanded the definition of ADHD to include adolescents. It was further subdivided into two categories: ADD with hyperactivity and ADD without hyperactivity. In 1987, the subtypes were removed, and the disorder became known as ADHD.
Cases began to climb significantly in the 1990s. This may be partly due to doctors being able to diagnose the condition more readily, as well as to increased awareness of the condition, in part helped by famous individuals going public with their own diagnosis of ADHD.
Statements by celebrities such as Johnny Depp, Emma Watson and Michael Phelps are likely to have reduced the stigma and led to demand among adults and children to be tested for the condition. This may have fuelled the increase in diagnoses and suspected cases we now see.
The current UK population prevalence estimate is 5% among 10- to 14-year-olds and 3%-4% among adults.1 This equates to around 2.6 million people in the UK with an ADHD diagnosis. It is more commonly diagnosed in men than women, and women are thought to be better at ‘masking’ the condition.
The current DSM-5 defines ADHD as showing a pattern of inattention and/or hyperactivity-hyper impulsivity that interferes with functioning or development. The condition has no known cause but does appear to run in families.
NICE proposes the following criteria for a case of ADHD, based on expert opinion and the DSM-52: Suspect attention deficit hyperactivity disorder (ADHD) if there are at least six (five in adults) inattention symptoms and/or at least six (five in adults) hyperactivity-impulsivity symptoms that have:
- Started before 12 years of age.
- Occurred in two or more settings such as at home and school.
- Been present for at least six months.
- Clearly interfered with, or reduced the quality of social, academic or occupational functioning.
- Not occurred exclusively during the course of a psychotic disorder and are not better explained by another disorder, such as oppositional defiant disorder or conduct disorder.
Inattention symptoms include:
- Failing to give close attention to detail or making careless mistakes in schoolwork, work or other activities.
- Difficulty in maintaining concentration when performing tasks or play activities.
- Appearing not to listen to what is being said, as if the mind is elsewhere, without any obvious distraction.
- Failing to follow through on instructions or finish a task (not because of oppositional behaviour or failure to understand).
- Difficulty in organising tasks and activities.
- Reluctance, dislike or avoidance of tasks that require sustained mental effort.
- Losing items necessary for tasks or activities such as pencils, mobile phones, or wallets.
- Easy distraction by extraneous stimuli.
- Forgetfulness with regards to daily activities.
Hyperactivity-impulsivity symptoms include:
- Fidgeting, tapping hands or feet, or squirming when seated.
- Leaving the seat where remaining seated is expected, such as in a classroom.
- Running about or climbing in situations where inappropriate, or feeling restless. In adolescents or adults this may be limited to a feeling of restlessness.
- An inability to play or engage in leisure activities quietly.
- Being ‘on the go’ or acting as if ‘driven by a motor’. Others may experience the person to be restless or difficult to keep up with.
- Talking excessively.
- Blurting out an answer before a question has been completed.
- Difficulty waiting in turn.
- Interrupting or intruding on others.
Full diagnostic criteria can be found in the DSM-5.3
The symptoms of ADHD are more difficult to define in adults and tend to be subtler than in children. Generally, adults present less with hyperactivity but exhibit inattentiveness, carelessness, a lack of attention to detail, inability to prioritise and non-completion of tasks, forgetfulness and frequently losing things. Behavioural traits can include mood swings with flares of temper, extreme impatience and risk-taking behaviour.
Reasons for overdiagnosis
A misdiagnosis of ADHD can be made when symptoms overlap with other mental health and neurodiversity conditions, such as depression, OCD, bipolar disorder, anxiety and neurodiversity conditions like autism. Restlessness, sleep disturbance, irritability, mood swings and struggling in social situations are common to all these conditions.
Children may be misdiagnosed with ADHD because of relative immaturity compared with their peers.4 A younger child will not have the same attention span as a child many months older. Ineffective parenting and problems with family dynamic may lead to behavioural problems in children that are misdiagnosed as ADHD.
Personality disorders, neurodiversity, conduct disorder, abuse and underlying physical illness can all manifest with symptoms that overlap with ADHD. The pressure on teachers, parents and clinicians to arrive at a quick diagnosis may lead to a temptation to diagnose ADHD which has a single effective oral treatment – oral amphetamines.
Overdiagnosis of ADHD in adults, recently highlighted in a BBC Panorama documentary5, may occur for a number of reasons. The relative ease and subjectivity of self-diagnosis using online tools may be partly to blame. Some adults may ‘prefer’ to attribute their symptoms to ADHD than to conditions such as depression or anxiety. There may also be a temptation to medicalise behavioural traits like getting bored easily or making mistakes when undertaking repetitive tasks. The stimulant medications used to treat ADHD can make many people without ADHD feel better and focus more effectively. At the most basic level, many patients want an explanation and label for their symptoms, and for many ADHD can offer this.
Supporting a patient’s next steps
If a clinician suspects a misdiagnosis of ADHD, they should discuss this with the patient or parent and consider alternative explanations for their symptoms. It is important to explain to patients that a number of medical conditions have overlapping symptoms with ADHD and the diagnosis, unlike most medical diagnoses, is subjective.
Clinicians must remember to discuss possible implications of a diagnosis of ADHD with patients requesting a referral. Patients should understand that the diagnosis would remain on their medical records forever and could have implications for their future. It is important to discuss with patients, particularly parents of children, the possibility that what may be seen as ‘ADHD symptoms’ are just variations of normal behaviour.
- Sayal K et al. ADHD in children and young people: prevalence, care pathways, and service provision.Lancet Psychiatry 2018;5,175-186. Link
- NICE Clinical Knowledge Summary. When should I suspect ADHD? November 2022. Link
- American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 5th edition. Arlington, VA., American Psychiatric Association, 2013. Link
- Ford-Jones PC. Misdiagnosis of attention deficit hyperactivity disorder: ‘Normal behaviour’ and relative maturity. Paediatrics & Child Health 2015;20, 200–2. Link
- BBC TV. Panorama: Private ADHD Clinics Exposed. May 2023. Link
Dr David Turner is a GP in Hertfordshire and a Pulse columnist. Read his blogs here