The relationship between olfactory dysfunction and executive function in children with traumatic brain injury.

INTRODUCTION: Olfactory dysfunction (OD) has been suggested as a possible marker of executive function (EF) deficits after traumatic brain injury (TBI) in adults. Little is known about the relationship between EF and OD in pediatric TBI (pTBI). This study aimed to investigate EF, explore the relationship between OD and EF, and determine the utility of olfactory performance as a marker of later EF in pTBI. It was hypothesized that (i) children with TBI would perform more poorly on EF measures relative to normative expectation; (ii) children with OD would perform more poorly on tests of EF than those with normal olfaction after TBI; and (iii) acute olfactory function would predict later EF for children with TBI.

METHOD: This was a prospective longitudinal study. Twenty seven children aged 8-16 with TBI completed olfactory assessment using the University of Pennsylvania Smell Identification Test at 0-3, 8 and 18 months post injury. Assessment of EF occurred at 8 and 18 month follow-up.

RESULTS: At 8 month follow-up the pTBI cohort did not demonstrate a consistent pattern of impairment in EF, contrary to our first hypothesis. Children with OD showed significantly poorer performance on a single EF measure of Fluency when compared to those with normal olfaction at 8 months post injury, partially supporting our second hypothesis. Acute olfactory function did not significantly predict EF outcomes at either 8 or 18 months post injury.

CONCLUSIONS: Overall our findings provide little support for a significant relationship between EF and OD in pTBI. In particular, there was no strong evidence that acute olfactory function is an accurate predictor of later EF in pTBI. Given the dearth of pediatric research, the limitations of our study and the potential significance of acute olfactory performance as an early marker of later EF deficits in children, further investigation is warranted.