PURPOSE: The neural substrate of post-concussive symptoms following
the initial injury period after mild traumatic brain injury (mTBI) in
pediatric populations remains poorly elucidated. This study examined
neuropsychological, behavioral, and brain functioning in adolescents
post-mTBI to assess whether persistent differences were detectable up to a
year post-injury.
METHODS: Nineteen adolescents on average 7.5 months post-mTBI
completed neuropsychological testing and an fMRI auditory-verbal N-back
working memory task. Parents completed behavioral ratings. The comparison
group included 19 healthy controls matched to the mTBI group for demographic
variables and N-back task performance.
RESULTS: There were no between-group differences for cognition or
behavior ratings. The expected decreased accuracy and increased reaction
time as N-back task difficulty increased were apparent. The mTBI group
showed significantly greater brain activation than controls during the most
difficult working memory load condition.
CONCLUSION: Greater working memory task-related activation was
found in adolescents up to one year post-mTBI relative to controls,
potentially indicating compensatory activation to support normal task
performance. Differences in brain activation in the mTBI group so long after
injury may indicate residual alterations in brain function much later than
would be expected based on the typical pattern of symptom recovery, which
could have important clinical implications.
