ADHD - Diagnostic methods
Author: Ulrich Brennecke
Review: Dipl.-Psych. Waldemar Zdero (08/2024)
An ADHD diagnosis is traditionally determined using questionnaires, interviews and tests. In principle, several different instruments should be used. This means that several questionnaires, several tests and a personal interview by the diagnostician are essential for a good diagnosis.
The agreement between questionnaires and tests is limited despite the validity and reliability of the respective tests being checked.
Symptoms of ADHD also occur in other disorders. A study of 10 disorders found that 60% of the symptoms occurred in at least half of all disorders and were assessed in the respective disorder-specific questionnaires and tests.1
ADHD is typically diagnosed by the number of relevant symptoms. This increases the diagnostic accuracy of ADHD.2 This model was exemplified by Barkley:
- Non-affected people often have 1 to 2 of 18 symptoms on average (around 5%)3
- On average, people with ADHD often have 12 of these 18 symptoms (around 66%)3
The online screening of the ADxS.org symptom test is based on this model. The test queries 45 symptoms, but is not medically validated and is not used for medical diagnosis.
Neuropsychological tests4 or individual biomarkers are too imprecise to diagnose ADHD. We suspect that, similar to the rating scales for symptoms of ADHD, which are based not only on a single symptom but on the cluster of symptoms common in ADHD, a test cluster of a group of neuropsychological tests or measurement of a group of biomarkers typical of ADHD could result in adequate test accuracy. Since ADHD is a syndrome, i.e. a multitude of different causes that manifest themselves in common symptoms, biomarkers should only be able to measure either the mechanisms that mediate the common symptoms (although here too, with the dopamine and noradrenaline systems alone, there are several similar, because functionally redundant, systems) or individual causes of the syndrome, but barely all of them. Against this background, it is surprising that the improvement of the detection rate through individual biomarkers continues to be pursued instead of researching the appropriate combination of different biomarkers that, in their entirety, enable ADHD diagnostics. There are individual approaches that pursue this idea.56
Newson, Hunter, Thiagarajan (2020): The Heterogeneity of Mental Health Assessment. Front Psychiatry. 2020 Feb 27;11:76. doi: 10.3389/fpsyt.2020.00076. PMID: 32174852; PMCID: PMC7057249. ↥
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Barkley, Benton (2010): Das große Handbuch für Erwachsene mit ADHS, Huber, Seite 46; n = 252 ↥ ↥
Barkley (2023): Assessment of ADHD in Children and Teens. Youtube. 48:30 / 01:33:000 ↥
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