Visual illusion susceptibility following mild traumatic brain injury in adolescents

Abstract

Following Mild Traumatic Brain Injury (mTBI), clinical symptoms often resolve before full physiological recovery is complete, highlighting the need for objective indicators of ongoing neural disruption. Visual illusions, which rely on contextual visual processing, may provide a sensitive behavioural marker of subtle perceptual changes following concussion. While reduced susceptibility to visual illusions has been demonstrated in adults following mTBI, little is known about whether similar effects are observed in adolescents. The present study examined susceptibility to visual illusions in adolescents with a history of mTBI and in a TBI-free comparison group. A secondary aim was to explore associations between illusion performance, age, and post-concussive symptom burden within the mTBI group. Adolescents with a history of mTBI and age-matched TBI-free comparison participants completed two visual illusion tasks (Ebbinghaus and Müller–Lyer), each comprising context (illusion) and no-context trials. Post-concussion symptoms were assessed using developmentally appropriate versions of the Post-Concussion Symptom Inventory (PCSI). No significant group differences were observed on context trials of either illusion task. Adolescents with mTBI showed significantly lower accuracy on no-context trials of the Ebbinghaus task than comparison participants. Age was not significantly associated with illusion susceptibility in either group. Within the mTBI group, post-concussion symptom severity was not significantly related to performance on Müller–Lyer or Ebbinghaus context trials for either parent-reported or adolescent self-reported symptoms. These findings suggest that visual integration accuracy appears comparable to typical performance in adolescents assessed at a relatively long interval following mTBI, which may reflect recovery or resolution of any earlier disruption. However, whether visual integration was affected during the acute or subacute stages of injury remains unclear. Future research is needed to determine whether visual-illusion paradigms provide a useful, objective complement to symptom-based assessment for detecting subtle perceptual differences following paediatric mTBI.