Predicting blink rate and pupil diameter from ADHD symptoms: Effects of white noise stimulation in an experimental study

• No relationship was found between ADHD symptoms and blink rate or pupil size. • Auditory white noise stimulation influenced pupil size but not blink rate. • Boys had larger pupil diameters, especially during auditory white noise stimulation. • Results suggest sex differences should be considered in noise intervention studies. Children with ADHD are reported to have lower dopamine (DA) and norepinephrine (NE) levels compared to typically developing children. We exploratively investigated how blink rate and pupil diameter, which are considered to be proxies for DA and NE signaling, were related to ADHD symptom severity. Moreover, we tested whether this relation is modulated by auditory white noise stimulation, which has been suggested as a non-pharmacological treatment for children with ADHD. We measured blink rate and pupil diameter in 97 children with varying levels of ADHD symptoms during a 60 s fixation task. The task was performed with and without auditory white noise stimulation. The effect of white noise stimulation was evaluated in relation to symptom severity and task duration. We found no relationship between the level of ADHD symptom severity and blink rate or pupil diameter, nor did symptom severity interact with auditory white noise stimulation. However, pupil diameter was consistently larger throughout the entire task as a result of the noise stimulation, an effect driven by boys. Blink rate and pupil diameter do not seem to be reliably associated with ADHD symptom severity. This association also did not change when applying white noise stimulation. However, given the larger pupil diameter of boys, sex should be considered in future studies using white noise stimulation.