Are people with ADHD and OCD similar when it comes to dealing with change?

When we think of ADHD and OCD, we tend to imagine them as two different worlds: one associated with impulsivity and the search for novelty; the other with rigidity and fear of making mistakes. Therefore, we tend to assume that those with ADHD are “too changeable” (changing plans every two minutes, jumping from one activity to another without finishing what they have started) and that those with OCD are “too rigid” (following exactly the same order, being very strict with schedules). In both cases, we are talking about a problem of cognitive flexibility. But is this something that affects all people with OCD or ADHD equally? What happens when they face situations where the rules change and they have to adapt?

These questions guided a study we published this year in Comprehensive Psychiatry (https://linkinghub.elsevier.com/retrieve/pii/S0010-440X(25)00016-1). To do this, we used computational models to try to understand how we learn rewards and punishments and a neuroimaging technique (fNIRS) to measure brain activity at rest. We wanted to explore whether there are common mechanisms between ADHD and OCD and, if not, what differentiates them when it comes to learning and readjusting behavior. In our study, 43 adults with OCD, 53 with ADHD, and 52 people without a diagnosis completed a task designed to measure “flexibility”: participants had to choose between two colors, one that gave points most of the time and another that took them away; but after a few rounds, the rules changed and the “good” color became the other one.

What did we discover?

Both the ADHD and OCD groups took longer to detect this change and adjust their behavior. So far, similar results. But the reason why they struggled was not the same.

In OCD, punishment weighed heavily. The idea of “losing 5 points” had a clear effect on their decisions. In ADHD, on the other hand, immediate reward was the driving force. Interestingly, OCD, traditionally associated with rigidity, did not show perseveration here. Rather, they tried to adapt, but sensitivity to punishment had such an influence that it hindered the process.

What does brain connectivity tell us?

Before starting the task, we recorded brain activity at rest for nine minutes. Just looking at a fixed point. In people without a diagnosis, communication between the left and right parietal areas predicted how well they would later learn how well they would later learn which color gave the most points. A balance in that connectivity seemed to help better integrate information about punishments and rewards.

Why is this useful to know?

Our data points to something that can be very useful in therapy: reducing uncertainty helps. Providing clear instructions, structuring information, or anticipating possible situations of change can make it easier for people with ADHD or OCD to better adapt their behavior. In addition, understanding which mechanism predominates in each person opens the door to more tailored interventions that go beyond the diagnostic label.