Traumatic brain injury, post-traumatic stress disorder symptom reporting and attentional bias: unravelling the misidentification of post-traumatic stress disorder in people with a traumatic brain injury

Background: Post-traumatic stress disorder (PTSD) can occur following a traumatic event that has led to moderate to severe traumatic brain injury (TBI) even when there is little or no memory for the event. The incidence of PTSD is higher when diagnosed by self-report questionnaires compared to structured clinical interview. Previous studies suggest PTSD can be misdiagnosed in a significant proportion of cases and the incidence is in fact low. To explore this issue further there is a need to not only understand whether there are differences between cases that do and do not fulfill symptom criteria for PTSD, but also whether some cases have ‘partial PTSD’; that is to say they have PTSD symptoms but do not fulfill the DSM-IV symptom criteria exactly. Aims: The study aims to establish whether an attentional bias to trauma related words exists in people with TBI who report PTSD symptoms and to investigate the relationship between physiological arousal and attentional bias in people with a TBI reporting PTSD symptoms. Method: Forty-one participants with severe-extremely severe TBI were recruited from the community and completed measures of cognitive functioning. Attentional bias was measured using a Stroop task in which trauma, negative, neutral and positive words were administered randomly. Physiological reactivity (heart rate) was recorded and PTSD ‘caseness’ was established using a self-report questionnaire and a clinician-administered structured interview. Results: No significant relationship between PTSD symptom severities and attentional bias to trauma stimuli was apparent. Those with ‘PTSD’ demonstrated significantly slower reaction times to negative words however; this bias was associated with self-report of depression rather than PTSD symptomatology. Heart rate decreased throughout the interview and was not associated with PTSD symptom severities. Conclusions: Greater PTSD symptom reporting was not associated with an attentional bias to trauma words. Heart rate decreased over the course of the interview, independent of PTSD severity and diagnosis. This suggests that ‘partial’ PTSD was not present, and instead those who reported PTSD symptoms were curious about the gap in memory caused by amnesia without the associated fear response