Objective To compare working memory performance and related brain activity using fMRI in concussed youth and healthy age-matched control subjects.

Design Standard T₁ and T₂* weighted echo planar images for blood oxygenation level dependent (BOLD) were collected on a 3Tesla System with a 32 channel head coil while subjects performed verbal and nonverbal working memory tasks. fMRIstat was used to analyse the data.

Setting Participants were purposively recruited between 2007 and 2010 from The Montreal Children's Hospital Trauma Programs.

Subjects 15 concussed youth (8 females, 7 males, mean age=14.47±2.29 years) and 15 age-matched control subjects (7 females, 8 males, mean age=14±2.3 years).

Intervention None.

Outcome Measures Post-Concussion Scale—Revised, accuracy and reaction time (RT) on a verbal and nonverbal working memory task.

Results Post-concussion symptoms were higher for concussed versus control participants. The concussed group demonstrated significantly poorer accuracy but equivalent RT on the working memory task. Greater percent BOLD signal change from baseline to task was observed for control versus concussed participants in the left and right dorsolateral prefrontal cortex, left premotor cortex, dorsal anterior cingulate cortex, supplementary motor area, left superior parietal lobule, left thalamus and left caudate nucleus. Activity in the left and right dorsolateral prefrontal cortices positively correlated with task accuracy.

Conclusions Compared to adults, concussed youth may be unable to engage to the same extent compensatory strategies to maintain cognitive performance following neuronal injury. Greater caution in clinical management is therefore recommended.

Acknowledgements Canadian Institute of Health Research (CIHR) and Ontario Neurotrauma Foundation (ONF).

Competing interests None.