Altered Relationship Between Microsaccades and Inattention in ADHD and the Effects of Stimulant Medication

Abstract Objectives Research into the role of the oculomotor system in attention deficit hyperactivity disorder (ADHD) has grown recently, but studies examining microsaccades are limited and contradictory, with tasks often confounded by high cognitive load. The current study aimed to explore the relationship between microsaccades and ADHD traits in adults with a diagnosis of ADHD, both those receiving medication (ADHD-M) and those who were unmedicated (ADHD-U), and a healthy control (HC) group. Methods All participants (ADHD-M, N = 18; ADHD-U, N = 22; HC, N = 31) completed the Adult ADHD Self Report Scale and a simple sustained attention task whilst binocular microsaccades were measured in a cross-sectional study. Results A significant positive correlation was found between total ASRS score and microsaccade rate for the HC group, driven by a correlation between inattentive traits rather than hyperactive/impulsive traits. The same relationship between inattention and microsaccade rate was found for the ADHD-M group but not the ADHD-U group, who showed an opposite relationship. Conclusions This research aligns with previous work finding that it is inattentive symptoms which are related to microsaccade features and demonstrates the need to consider medicated and unmedicated groups separately, which may have contributed to mixed findings previously. The findings here suggest that medicated individuals with ADHD show comparable microsaccade-inattention trait relationships to healthy controls which warrants further investigation to establish if medication normalises this relationship. Similarly, the distinct pattern of results for unmedicated individuals should be explored further in the context of conceptualisation of ADHD traits as a continuum.