Pink Noise and a Pure Tone Both Reduce 1/f Neural Noise in Adults With Elevated ADHD Traits: A Critical Appraisal of the Moderate Brain Arousal Model.

The moderate brain arousal (MBA) model posits that individuals with (elevated traits of) ADHD have lower levels of neural noise and that auditory random noise can elicit stochastic resonance (SR) and increase neural noise, which improves their cognitive performance. Indeed, research shows that auditory random noise, such as white noise, improves cognitive performance in individuals with (elevated traits of) ADHD. However, the assumptions regarding neural noise in ADHD and the requirement of SR have been insufficiently examined due to a lack of studies incorporating both a second non-random auditory condition and an index of neural noise. Therefore, 69 neurotypical adults completed the ASRS to assess ADHD traits and underwent eyes-closed resting-state EEG, subdivided into three 2-min blocks: silence, continuous auditory pink noise (a random signal), and a continuous 100 Hz pure tone (a non-random signal). We then analyzed the aperiodic slope of the EEG power spectral density, a proposed direct measure of neural noise. Pink noise affected the aperiodic slope differently based on ADHD traits; specifically, it increased the slope in individuals with elevated ADHD traits, indicating a decrease in neural noise. Crucially, the same effect was observed for the pure tone. These findings challenge the MBA model by demonstrating that both random (pink noise) and non-random (pure tone) signals reduce neural noise in individuals with elevated ADHD traits, contradicting the proposed mechanism of stochastic resonance, as well as the direction of effects suggested by the MBA model. These findings warrant further investigation, also in a clinical ADHD sample.