The effects of fatigue and the post-concussion syndrome on executive functioning in traumatic brain injury and healthy comparisons

In this study, behavioural manifestations of compromised executive control, including perseveration and reduced inductive reasoning, on the Wisconsin Card Sorting Test (WCST) were investigated.Performance was affected by fatigue in both a head-injured and matched population, which has implications for health care professionals involved in rehabilitation and assessment. A fatigue condition was manipulated for 15 moderate to severe traumatic brain injury (TBI) individuals through the course of a three-hour neuropsychological testing session. A comparison sample of 15 participants in a group of ‘no history of TBI’ was fatigued through the same approach. All fatigued participants (with and without TBI) displayed trends towards increased levels of perseveration and reduced inductive reasoning on the WCST. Thus, the effects of fatigue on high-level functioning are pervasive even when not head-injured. This finding supports the sub-optimal performance in cognitive skills, specifically in executive control, that is often found in fatigued people. These findings are relevant for the manner in which rehabilitation interventions and medico-legal assessments are structured. Importantly, the order of tests, their interpretation and rest sessions should be clearly indicated and interpreted in assessment reports and rehabilitation sessions.OpsommingIn hierdie studie is gedragsmanifestering in individue met gekompromitteerde uitvoerende funksionering, met inbegrip van perseverasie en verminderde induktiewe redenering, op die Wisconsin-kaartsorteringstoets (WCST), bestudeer. Die waarneming dat prestasie deur uitputting beïnvloed word in sowel normale populasies as dié met kopbeserings het implikasies vir gesondheidsorgpersoneel wat by rehabilitasie en assessering betrokke is. ’n Uitputtingstoestand is gemanipuleer vir 15 matig ernstige individue met traumatiese kopbeserings (TKB) vir die duur van ’n drie uur lange toetssessie. ’n Vergelykingsmonster van 15 deelnemers met geen geskiedenis van kopbeserings is deur dieselfde metodologie uitgeput. Alle uitgeputte deelnemers (met en sonder TKB) het ’n neiging na verhoogde vlakke van perseverasie en verminderde induktiewe redenering op die WCST getoon. Die impak van uitputting op hoëvlak-funksionering is dus verreikend, selfs in gevalle waar geen kopbesering opgedoen is nie. Die bevinding ondersteun suboptimale prestasie in kognitiewe vaardighede, en spesifiek in uitvoerende beheer, wat dikwels onder uitgeputte mense gevind word. Hierdie bevindinge is van belang vir die manier waarop rehabilitasie-intervensies en regsgeneeskundige assesserings gestruktureer word. Die volgorde van toetse, die interpretasie daarvan en die rusperiodes moet duidelik in assesseringsverslae en rehabilitasiesessies aangetoon en geïnterpreteer word.