Over the past 15 years, the number of ADHD diagnoses has risen sharply in Sweden. Is this development reasonable? And what might be the cause? Whilst asking these questions, researchers would also like us to focus less on the diagnosis and more on the functional capacity of people with ADHD.
Text by: Annika Lund, first published in Medical Science No 3 2024
Attention deficit disorder and hyperactivity with poor impulse control. These are the most common symptoms of ADHD, attention deficit hyperactivity disorder.
As early as 1775, a German doctor described how some children had great difficulty maintaining their focus. 'Every buzzing fly, every shadow, every sound and memory distracts his attention to other thoughts. Even his own imagination entertains him with thousands of little pranks,' wrote Melchior Adam Weikard in a medical textbook, translated from an issue of the Swedish medical magazine Läkartidningen about ADHD.
Over the next two centuries, there were repeated descriptions published of how the main symptoms of ADHD often occur together. These descriptions were based on observations of the time and only in boys. Similarly, when the diagnostic criteria were developed in the 1970s, they were designed in a way that captured the symptoms observed in boys. And initially, it was mainly boys that were diagnosed.
Since then, dogged research has produced a more nuanced picture. Today, we know that ADHD occurs in both sexes and that it also occurs in adults. It is also known that there are differences between the sexes and age variations in how the symptoms usually manifest themselves (see box opposite).
It is well known that ADHD can vary in severity and that there are different forms of the condition. Some people only struggle with paying attention. This is called ADD, more common in girls and discovered at a higher average age than ADHD. ADHD also has a co-morbidity with other diagnoses. This makes ADHD a very heterogeneous condition. The diagnosis provides little guidance to those who want to understand the struggles an individual with ADHD faces.
ADHD an increasingly common diagnosis
This heterogeneous condition has become more common, in fact- much more common. The increase has been 'exceptional' since 2006, according to the wording of the National Board of Health and Welfare. The Board provides a review of the statistics in its report Diagnosis and medical treatment of ADHD. In 2022, 10.5 percent of boys and 6 percent of girls aged 10 to 17 had ADHD or ADD. And that figure is expected to increase. According to the National Board of Health and Welfare, 15 percent of boys and nearly 11 percent of girls are expected to have a diagnosis before the increase levels off.
What is the reason behind this exceptional increase? Have problems with concentration and volatile restlessness become much more common over the course of a few decades?
Facts: Same symptoms can manifest differently
ADHD is a neuropsychiatric disorder. The core symptoms of ADHD, attention deficit disorder with or without hyperactivity/impulsivity, can present differently.
- In boys, hyperactivity and impulsivity might show, as difficulty sitting still. In girls and women, the symptoms may be more verbal, such as interrupting or saying thoughtless things. In girls, hyperactivity may also be more related to fine motor skills, such as chewing on a pen or pulling apart a rubber.
- In adults, hyperactivity may manifest as an inner sense of restlessness, an inability to settle down.
- Attention deficit disorder manifests itself in similar ways in both sexes, in both children and adults. It can manifest itself as a difficulty in listening and taking in information.
- ADHD in older people is less researched. Other aspects of attention deficit disorder may come into focus, such as forgetfulness. It can sometimes be confused with symptoms of dementia.
- For a diagnosis of ADHD, the symptoms must be so severe that they cause a disability in everyday life. Other criteria must also be met for a diagnosis (read more in the main text).
- There are other symptoms common to ADHD that are not included in the diagnostic criteria. For example, many people have difficulty regulating emotions. Various sleeping problems are also common in ADHD.
Source: Lotta Borg Skoglund and others.
'No,' says Professor Sven Bölte , head of KIND, a centre of excellence for research, development and training in neuropsychiatric disabilities at Karolinska Institutet.
"The symptoms we are talking about ‒ attention deficit disorder, hyperactivity and lack of impulse control ‒ have not become more common. The prevalence of these ADHD traits seems to be fairly constant in the population," he says.
Several Swedish studies have backed this up. They are based on data from the Swedish Twin Registry. These include valuations of nine-year-old children, made through telephone interviews with the parents. The valuations look at core symptoms, such as how easy it is for children to listen, sit still in the classroom or wait for their turn. The answers are summarised into a rating of ADHD symptoms. According to the valuations, which cover children born since 1992, the prevalence of ADHD traits has remained relatively stable over time.
But there has been a very sharp increase in diagnoses.
It seems that more people are falling within the diagnostic criteria, even though the prevalence of symptoms remains at about the same level.
The National Board of Health and Welfare's report states that it is unclear why this is the case. Sven Bölte says the same, although he describes several possible causes. He says the following in response to the obvious question of whether there is increasing overdiagnosis or not:
"I do not think anyone is diagnosed with ADHD without any symptoms. However, some people who have problems with concentration, activity levels, and the ability to structure their work or studies might be helped through fairly minor interventions. If we could learn to recognise this in schools and workplaces, without anyone needing a diagnosis, we might return to a level where only the most pronounced cases receive a diagnosis, as it used to be."
He adds:
"A widespread misconception is that ADHD is an issue that concerns the health care sector alone. This leads to the idea that shorter waiting times for assessment and better access to medication are the most important factors to address ADHD. And those are important, absolutely. But more importantly, we need to understand that ADHD is an issue that concerns us all. The way we organise society will affect the number of ADHD diagnoses, same as how included people with ADHD feel. A high level of inclusion means reduced suffering and lower costs to society. A low level of inclusion means the opposite. We need to ask ourselves how we want it to be,' says Sven Bölte.
Diagnosis requires lasting symptoms
The symptoms that characterise ADHD are not unique to the condition. Everyone can be unfocussed, agitated or impulsive at times. For an ADHD diagnosis to be made, the problems must be significantly greater and more persistent than what is considered normal.
An important part of an ADHD assessment is an investigative interview conducted by a psychologist or psychiatrist. Along with other information gathered, it provides answers to whether the diagnostic criteria are met.
In order for the diagnosis criteria to be met, the symptoms must have existed for at least six months and have appeared before the age of 12. They should not be able to be explained by something else, such as stress or anxiety, which can also affect, for example, concentration or planning ability. The challenges should be greater than what can be expected for the age and noticeable in several contexts, such as both at home and school.
And, importantly, the problems should cause a functional impairment in everyday life. It is thus stated in the diagnostic criteria themselves that the diagnosis is made in a context, in relation to how everyday life functions.
One possible thought is that society has changed rather than its inhabitants, says Sven Bölte.
"It has become tougher to have traits of ADHD. Our society has become faster and more complex, which creates difficulties for those with poor time perception and struggles to structure their work or studies. In school, pupils are expected to solve tasks in groups or as part of projects from an early age; while grading systems are unclear, levels of freedom are hard to interpret, and staff have lost authority. These are also pieces of the puzzle of an increasing number of diagnoses,' he says.
Furthermore, increased awareness of the diagnosis has led to more parents and school staff requesting assessments. In addition, the increase has been significant among women, who were previously underdiagnosed.
ADHD now more common in women in Sweden
According to the National Board of Health and Welfare's report, anADHD diagnosis is now more common in women than in men. A review of the gender distribution at different ages shows that until late adolescence, ADHD is more common in boys, but thereafter women are in a slight majority.
"This is where Sweden differs from the international picture. In Sweden, there has been a lot of attention to the fact that ADHD is underdiagnosed among women. This has driven a strong trend of more diagnoses among women," says Sven Bölte.
According to the National Board of Health and Welfare, ADHD care is very unevenly distributed in the country. On Gotland, 7.3 percent of girls and 10.9 percent of boys aged 10 to 17 receive ADHD medication. These are the highest figures in the country. The lowest in the country is Region Västernorrland. There, 2.9 percent of girls and 6.0 percent of boys take medication.
Who is actually doing it right? When can it be determined that the right number of cases in children and adults of each sex have been noticed and attended to?
Recently, an organisation for international scientific cooperation presented a consensus document on ADHD. It summarises 208 statements of fact that researchers consider to be scientifically sound.
According to this document, 5.9 percent of adolescents and 2.5 to 2.8 percent of adults have ADHD. The condition is described as equally common across the world d, but more prevalent in men than in women.
However, Sven Bölte, who has been involved in the development of this consensus document, believes it is rigid to focus on how many people 'should' have an ADHD diagnosis.
"The figures in the consensus document are drawn from epidemiological studies conducted at specific times in various societies. This is what it looked like then. But now we are in a different time," he says.
Sven Bölte wants to move away from discussing the number of diagnoses. He repeatedly emphasises that the diagnosis only indicates that someone has a certain set of symptoms within the ADHD spectrum, not what the person can still do or how they are affected by their environment. This means that when an individual child is diagnosed with ADHD, the diagnosis itself does not provide enough information for school staff, for example. The same applies in the workplace and society, as a whole", says Sven Bölte.
"There are certain standard interventions to address the condition. For children, parents are offered parent training, and some children are offered medication. There are also some psychological treatment programmes. But it is rare that a person with ADHD is offered a review of their specific situation and then receives individualised information and suggestions with follow-ups over time, if it ever happens. But it is possible to achieve this. It is not even rocket science," he says.
Symptom mapping facilitates individualized support
Sven Bölte is hardly the first to point out the limitations of the diagnosis concept. As early as 1973, WHO made a principled decision to introduce a complementary system, alongside the ICD classifications of diagnosis. This system is called ICF and classifies functions. It concerns what works well or poorly for an individual, in that individual's life.
This system involves finding out how daily routines such as hygiene and cooking works for an individual, but also how sleep and social relationships function. It also involves identifying protective abilities and assets. Examples of these can be a supportive family or friends, social skills, various interests or high intellectual capacity. It can also be the ability to be easily motivated or the habit of being physically active.
"In a functional ability assessment, one tries to get a comprehensive picture of a person to then see in which situations things go well or less well," says Sven Bölte.
ICF is an extensive catalogue that includes descriptions of around 1,700 functions. To pinpoint those that may falter in ADHD, someone needs to sit down and sift through them. And then scientifically validate that selection.
Sven Bölte and his colleagues are working on this. What comes out of it is a core version of the ICF, ICF core sets, adapted specifically to ADHD. The researchers aim to produce both a short and a long version of a questionnaire, where the shorter one could be used in schools, for example. A vision is that pupils or parents fill it in before performance reviews or starting school. Teachers could then access summaries generated by the questionnaire. This could be done for all students, not just those with a diagnosis.
The researchers' goal is for each teacher to have better data in assessing the class they are teaching. Adjustments can be made based on this, sometimes with the help of student health services. One child might have things explained individually, another might receive tools to keep track of time, while a third might get a special seat in the classroom.
"The goal is to find a teaching method that works for everyone, both pupils and teachers. Teachers already make individual adjustments in the classrooms. ICF would make it possible to work more continuously and make assessments in a structured way according to an international standard. This could facilitate and increase the precision of the assessments that teachers already make,' says Sven Bölte.
He thinks that ICF, which is not yet available in an ADHD-adapted version, could also be used at work and by social services, for example. Moreover, it could be used repeatedly for the same individual, as functional levels are dynamic and influenced by various factors, from temporary sleep dips to changes in the environment and in life situation.
Anyone who is newly diagnosed should receive a more comprehensive review, according to Sven Bölte.
"In other areas, such as orthopaedics, it is obvious. Not everyone who has a certain type of fracture has the same need for support and adjustments, even though it is the same diagnosis. It is the same with ADHD,' he says.
Medication common
Medication is a very common intervention for ADHD. According to the National Board of Health and Welfare, about 75 percent of Swedish schoolchildren with ADHD start a medication treatment.
In the afore mentioned consensus document, nearly 50 of the 208 statements concern medication. Overall, ADHD medications are well-studied in rigorous research, showing they have few side effects and a good effect on ADHD symptoms in both adults and children. Some medications also reduce anxiety and improve the ability to regulate emotions. There is also evidence that young people who stop taking their ADHD medication get lower grades.
Facts: What is the cause of ADHD?
- Twin studies from several countries indicate that certain genes combined with certain environmental factors play a role in ADHD. Genetics, or heredity, plays a major role.
- There are several risk genes that, each on their own, play a small part in the development of ADHD.
- The environmental factors that are circled relate to exposure to various things during the foetal period or immediately after birth.
- ADHD is much more common in children who were born very or extremely premature and in children with low, very low or extremely low birth weight. High maternal blood pressure during pregnancy and pre-eclampsia also increases the risk of ADHD in the child. The same applies to maternal obesity and extreme obesity as well as hypothyroidism (underproduction of thyroid hormone) in the mother.
- Other environmental factors include exposure to toxic substances, where, for example, higher levels of lead in the blood of a child increase the risk of being diagnosed with ADHD. Poverty, stress and trauma also increase the risk of ADHD. For example, lower family income is linked to an increased prevalence of ADHD, as are deaths in the family. Furthermore, enterovirus is associated with an increased risk of ADHD.
Source: International consensus statement from the World Federation of ADHD.
Zheng Chang , a researcher at the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet, investigates the effects of ADHD medication. His research has shown that when people with ADHD take medication, the risk of premature death associated with the condition, decreases. This applies to all examined causes of death, but the risk of dying as a result of accidents or alcohol or drug overdoses decreases the most. However, it is common for people with ADHD, especially young adults to choose to discontinue treatment.
It is unclear why many choose to stop taking their medication. Some may give up due to side effects, such as sleep problems, loss of appetite, stomach pain, and headaches. Another possible reason could be fear of long-term side effects. Researchers now believe they can provide reassurance in this regard. The risk of cardiovascular disease is only elevated in those who take higher than normal doses for many years, and it is difficult to say whether this is due to the medication itself or other lifestyle factors.
More people discontinue medication in Sweden
There are variations between countries in how many people choose to stop taking their medication. Denmark stands out in this context. A study shows that one year after diagnosis, just over eight out of ten Danish children were still taking their medication, and after five years about half. This is significantly more than in Sweden.
ADHD medication starts working shortly after treatment starts, with a fairly immediate effect on symptoms. A possible explanation for why some people stop taking the medication could be that they do not experience symptom relief. This becomes apparent quite quickly.
Sweden and Denmark differ in several other ways too: in Sweden, more children are prescribed medication. At the same time, more children stop taking them.
"A possible interpretation is that Swedish doctors sometimes try giving ADHD medication for mild symptoms to see if it has an effect. If it does not work, the treatment is discontinued and something else is tried instead," says Zheng Chang.
The magazine Medical Science
The magazine Medical Science (Medicinsk Vetenskap) is published by Karolinska Institutet and targets the general public interested in medical science.
