Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder diagnosed when attention and / or hyperactivity problems interfere with a person’s functioning. It is a very common disorder: it affects approximately 5-7% of children across the western countries.


Before we get to the attention deficit, it would be interesting have a good understanding of attention. We all have a different attention span, but we have one thing in common: it is limited. Our attention is directed towards what interests us and the elements which are more salient in our environment. You can compare attention to a flashlight. Depending on where we point the light beam, we will be attentive to different aspects of our environment. The light beam of the person with ADHD tends to have difficulty staying focused on the same item.

Inattentional blindness
Causes of ADHD

The causes come from an interaction between genetics and the environment. A person having ADHD has a 75% risk of passing on the genes that are conducive to the development of this disorder to their child. Also, several correlations have been noted between certain environmental characteristics and the development of ADHD, but no causal link has been found.

Correlation: Observed link between two variables (eg: the more polluted the air, the more cases of ADHD = True)

Causality: Cause and effect link between two variables (eg: polluted air causes ADHD = We don’t know)

Environmental risk factors can arise from pregnancy to childbirth. Here are a few :

ADHD causes

Unlike other children, some areas of the ADHD child’s brain develop slower. Indeed, their frontal lobe therefore has a lower volume and activity than other children of the same age.


By adulthood, half of those diagnosed with ADHD will no longer have the deficit since their brains will have caught up and achieved typical neurological development.

ADHD False diagnosis

It may happen that a child who doesn’t have ADHD is wrongly diagnosed. I grouped the false diagnoses into three categories:

  1. Younger children in the class are more often wrongly diagnosed with ADHD because their problem behaviors are more reported by teachers. However, it’s normal for them to have more difficulty maintaining their attention since their frontal lobe is less developed than their class mates because of their younger age.

  2. Children aged 3 and under watching television for more than 2 hours a day are more likely to develop attention deficit similar to ADHD.

  3. Some disorders can be mistaken for ADHD. Very anxious children may seem inattentive when they are focusing on their anxiety-provoking thoughts. Language impairments can decrease understanding of instructions giving the impression that they did not listen to them. Child with superior intelligence can come with restless behavior because they lacks stimulation.

True ADHD vs False ADHD

However, these are errors that can be avoided by having a complete neuropsychological assessment before making the diagnosis.

English isn’t my first language so there might be some mistakes. If you want, let me know in the comments bellow if you found any so I can fix them. Thank you!

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American Psychiatric Association. (2013).Diagnostic and statistical manual of mental disorders DSM-5(5eéd.).

Flett, l. G., Kocovski.L.N, Davidson,C.G. et John, M.N. (2017). Introduction à la psychopathologie (1e éd.). Chenelière éducation.

Hammarrenger, B. (2020). TDAH. Association québecoise des neuropsychologues.

Ponnou, S., Kahout-Diazet, M. et Gonon, F. (2015). Le trouble déficitaire de l’attention avec hyperactivité dans la presse spécialisée destinée aux travailleurs sociaux : évolution des discours psychanalytiques et biomédicaux. Les dossiers des sciences de l’éducation, (34)139-154. DOI : 10.4000/dse.1219

Tamana, S.K., Ezeugwu, V., Chikuma, J., Lefebvre, D.L., Azad, M.B., Moraes, T.J., Subbarao, P., Becker, A.B., Turvey, S.E., Serars, M.R., Dick, B.D. Carson, V. et Rasmussen, C. (2019). Screen-time is associated with inattention problems in preschoolers: Results from the CHILD birth cohort study. PLoS ONE, 14(4). DOI : 10.1371/journal.pone.0213995

Touzin, C. (2018, 20 novembre). TDAH: forte hausse de la consommation de médicaments. La Presse.

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