Physiological emotional under-arousal in individuals with mild head injury

Abstract

Primary objectives: This study examined the potential emotional sequelae following self-reported mild head injury (MHI; e.g. ‘altered state of consciousness’ [ASC]) in university students with a particular focus on arousal status and responsivity to experimental manipulation of arousal.

Research design: A quasi-experimental design (n = 91) was used to examine arousal status (self-reported and physiological indices) and response to manipulated arousal (i.e. induced psychosocial stress/activation; reduced activation/relaxation) between persons who acknowledged prior MHI and persons with no-MHI.

Main outcome and results: University students who self-reported MHI were physiologically under-aroused and less responsive to stressors (both laboratory and environmental) compared to their no-MHI cohort. Those with reported loss of consciousness demonstrated the most attenuated emotional arousal responses (i.e. flattened electrodermal responsivity) relative to those with only a reported ASC, followed by those with no-MHI.

Conclusions: The under-arousal in traumatic brain injury has been hypothesized to be associated with ventromedial prefrontal cortex disruption. This under-arousal may be mirrored in persons who self-report experiencing subtle head trauma. Students who reported MHI may be less able to physiologically respond and/or cognitively appraise stressful experiences as compared to their no-MHI cohort; and experience subtle persistent consequences despite the subtle nature of the reported head trauma.

• arousal
• electrodermal activity
• mild head injury
• stress

Notes

1. Although the prevalence of MHI makes up more than half of this sample, previous research (e.g. 39.4% MHI [79]; 51% MHI [80]; 30% MHI [68]; 41% MHI [81]) has shown similar proportions when using this liberal criterion of ‘altered state of consciousness’ in a university student population.

2. Studies [5,93] have reported that males are 1.5-times more likely to incur a head injury than females; further, males are twice as likely as females to incur a mild head injury, especially from 15–24 years of age.