Investigating the effects of arousal state on cognitive performance in individuals with and without mild head injury
Abstract
We examined the cognitive and emotional sequelae following mild head injury
(MHI; e.g., concussion) in high-functioning individuals and whether persons with MHI
pre~ent, both physiologically and via self-report, in a manner different from (i.e.,
underaroused) that of persons who have no history of head injury. We also investigated the
effect arousal state ~as on the cognitive performance of this population. Using a quasiexperimental
research design (N = 91), we examined changes in attention, working
memory, and cognitive flexibility (subtests ofthe WAIS-III, 1997,WMS-III, 1997, &
DKEFS, 2002) as a function of manipulated arousal (i.e., induced psychosocial
stress/activation; reduced activation/relaxation). In addition to self-reported arousal and
state anxiety (State-Trait Anxiety Inventory; Speilberger, 1983a) measures, physiological
indices of arousal state (i.e., electrodermal responsivity, heart rate, and respiration activity)
were recorded (via Polygraph Professional Suite, 2008) across a 2.5 hour interval while
completing various cognitive tasks. Students also completed the Post-concussive Symptom
Checklist (Gouvier et aI., 1992). The results demonstrate that university students who
report a history ofMHI (i.e., "altered state of consciousness") experience significantly
lower levels of anxiety, were physiologically underaroused, and were less responsive to
stressors in their environment, compared to their non-~HI cohorts. As expected, cognitive
flexibility (but not other neuropsychological measures of cognition) was advantaged with
increased stress, and disadvantaged with reduced stress, in persons with reported MHI, but
not for those without reported MHI which provided limited support for our hypothesis.
Further, university students who had no complaints related to their previous MHI endorsed
a greater number of traditional post-concussive symptoms in terms of intensity, duration
and frequency as compared to students who did not report a MHI.
The underarousal in traumatic brain injury has been associated with (ventromedial
prefrontal cortex) VMPFC disruption and may be implicated in MHI generally. Students
who report sustaining a previous MHI may be less able to physiologically respond and/or
cognitively appraise, stressful experiences as compared to their no-MHI cohort and
experience persistent, long-lasting consequences despite the subtle nature of a history of
head injury.