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The Dubious Increase In ADHD Diagnoses

Diagnostic figures for ADHD are rising almost everywhere. Are there really more children with “Fidgety Philipp syndrome” today? A Swedish study suggests otherwise.

Like an inner drive that never stands still, this is how those affected describe what happens in their heads. It is often almost impossible for people with ADHD to concentrate on one thing. And while the affected person’s brain constantly absorbs new external impressions that it cannot ignore, their body is also constantly in motion. Around the globe, about five percent of children currently suffer from ADHD, or “Fidgety Philipp syndrome.”

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It didn’t always look that way. The number of people affected seems to have been rising for decades. According to studies, Sweden, for example, experienced a sevenfold increase in diagnoses in ten-year-old children between 1990 and 2007 (1). Similar increases are also reported in other countries. In Germany, the frequency of ADHD diagnoses among 0 to 17-year-olds rose from 5.0 percent to 6.1 percent between 2009 and 2014 (with a maximum of 13.9 percent among 9-year-old boys) (2). If one takes the prescription frequency of Ritalin as a measure for ADHD diseases, a study from Great Britain came to even more far-reaching changes: in 2013, around 34 times more children under the age of sixteen took Ritalin than in 1990 (3).

How can such an increase be explained? Is a diagnosis made too early today? Or are ADHD symptoms actually more frequent? The latter was investigated by a Swedish study (4) with over 20,000 participants.

Scientists led by Mina Rydell of the Swedish Karolinska Institutet have been searching the data of an ongoing study with Swedish twins. Since 2004, the parents of all twins born in Sweden have been interviewed annually on the physical and mental condition of their children, as soon as they are nine years old (5). The interview also includes questions about possible ADHD symptoms, such as whether the child has difficulty keeping his or her hands still or sitting down. The Swedish researchers were able to identify different groups with this information. Those with clear ADHD symptoms, twins with subliminal characteristics or no ADHD symptoms at all.

Over a period of ten years (2004-2014), about 2.1 percent (406) of the participants (2004-2014) showed ADHD symptoms relevant to their diagnosis. There was no increase during this period.

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Nevertheless, the number of ADHD diagnoses made by physicians increased fivefold between 2004 and 2014 – a comparison of the scientists with data from the national patient register showed this. How can this be? The only significant change the Swedish researchers observed was in the subliminal ADHD symptoms. Between 2004 and 2014, their share rose from about ten percent to 14.76 percent.
However, if only mild forms of ADHD symptoms increase, then other factors, such as better access to the medical system, should be responsible for the increase in ADHD diagnoses according to this study. The greater attention the disease has received over the years may also play a role, as may overdiagnosis.

However, the weaknesses of the study should also be considered when interpreting the results. The data on which the study is based comes from interviews with parents, which is not the safest source of information. The fine distinction between normal childhood development and ADHD is often difficult to determine. Therefore, a diagnosis of ADHD always requires more than just observation from one’s parents. And also the fact that only twins were examined can have an effect on the study result.

This is part 34 of a series covering twin health provided by Paul Enck from the Tübingen University Hospital and science writer Nicole Simon. Further studies in twin research can be found at TwinHealth website. Translation was done with the assistance of DeepL translator.

References:

  1. Atladottir HO, Gyllenberg D, Langridge A, Sandin S, Hansen SN, Leonard H, et al. The increasing prevalence of reported diagnoses of childhood psychiatric disorders: a descriptive multinational comparison. Eur Child Adolesc Psychiatry. 2015 Feb;24(2):173-83.
  2. https://www.aerzteblatt.de/archiv/186552/ADHS-in-Deutschland-Trends-in-Diagnose-und-medikamentoeser-Therapie
  3. Beau-Lejdstrom R, Douglas I, Evans SJ, Smeeth L. Latest trends in ADHD drug prescribing patterns in children in the UK: prevalence, incidence and persistence. BMJ Open. 2016 Jun 13;6(6):e010508..
  4. Rydell M, Lundström S, Gillberg C, Lichtenstein P, Larsson H. Has the attention deficit hyperactivity disorder phenotype become more common in children between 2004 and 2014? Trends over 10 years from a Swedish general population sample. J Child Psychol Psychiatry. 2018;59: 863-71
  5. https://ki.se/en/meb/the-child-and-adolescent-twin-study-in-sweden-catss

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