Physiological emotional under-arousal in individuals with mild head injury.

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. [ABSTRACT FROM AUTHOR]