Are all children with ADHD impatient? One of our recent studies indicates that NO

One of the most widely held ideas about ADHD is that people with ADHD tend to be impatient: preferring immediate small rewards rather than waiting for something better (e.g. preferring to play a game on the console for five minutes rather than waiting an hour for half an hour without interruption). This phenomenon, known as delay aversion - or intolerance to waiting - is often associated with impulsivity, but is it something that affects all children and adolescents with ADHD equally?

As part of Pilar Fernández-Martín's doctoral thesis, we set out to explore this question further. In a study recently published in Nature Translational Psychiatry (link here), we analysed how children and adolescents with ADHD make decisions when they have to choose between an immediate reward and a larger, but delayed, reward. We wanted to find out whether there are different response profiles to waiting, and what the behavioural and neurobiological implications are.

In our study 43 children with ADHD and 47 children without ADHD completed a ‘delay discounting task’ developed by our group: a task in which they had to put themselves in the shoes of a pirate and choose which island to go to in order to get a treasure chest (a nearby island with a very small treasure chest or a distant island with a bigger chest).

What did we discover when we conducted the analyses?

We were able to identify different profiles of children (‘cluster analysis’) and found that there are five distinct groups:

• Two conventional groups, where the value of the reward decreases with waiting (in different intensity).

• And three atypical profiles: one with marked discounting (very marked aversion to waiting, ‘impatient’), one with mild discounting (little sensitivity to the passage of time), and one group with no discounting (where delay does not affect choice at all, very ‘self-controlled’).

How were the profiles distributed?

The 78% of children with combined ADHD were in the profiles with the highest delay aversion. In contrast, 42% of children with inattentive ADHD belonged to the mild or no discounting profiles. This indicates that not all children with ADHD respond in the same way to waiting, and that motivation can be expressed very differently depending on the clinical profile, especially in children with inattentive ADHD, who are a group with greater variability.

Regarding brain connectivity...

We analysed brain connectivity at rest using functional spectroscopy (fNIRS). Children with lower delay aversion showed hypoconnectivity between key brain networks for self-regulation and reward processing, such as the frontoparietal network and the default network.

These findings reinforce the need to understand ADHD not only from its visible symptoms, but also from its motivational and neurobiological mechanisms. A commitment to

a dimensional approach - beyond clinical labels - can help us to better personalise interventions and tailor support to the real needs of each child.