Abstract
Firefighters are frequently exposed to stressful situations and are at high risk of developing post-traumatic stress disorder (PTSD). Hyperresponsiveness to threatening and emotional stimuli and diminishment of executive control have been suggested as manifestations of PTSD. To examine brain activation in firefighters with PTSD by conducting an executive control-related behavioural task with trauma-related interferences. Twelve firefighters with PTSD and 14 healthy firefighters underwent functional magnetic resonance imaging (fMRI) while performing a Stroop match-to-sample task using trauma-related photographic stimuli. Seed-based functional connectivity analysis was conducted using regions identified in fMRI contrast analysis. Compared with the controls, the participants with PTSD had longer reaction times when the trauma-related interferences were presented. They showed significantly stronger brain activation to interfering trauma-related stimuli in the left insula, and had weaker insular functional connectivity in the supplementary motor area and the anterior cingulate cortex than the controls. They also showed a significant correlation between left insula-supplementary motor area connectivity strength and the hyperarousal subscale of the Clinician-Administered PTSD Scale. Our findings indicate that trauma-related stimuli elicit excessive brain activation in the left insula among firefighters with PTSD. Firefighters with PTSD also appear to have weak left insular functional connectivity with executive control-related brain regions. This aberrant insular activation and functional connectivity could be related to the development and maintenance of PTSD symptoms in firefighters.
Highlights
Firefighters are frequently exposed to stressful situations and are at high risk of developing post-traumatic stress disorder (PTSD)
Compared with the controls, the participants with PTSD had longer reaction times when the trauma-related interferences were presented. They showed significantly stronger brain activation to interfering trauma-related stimuli in the left insula, and had weaker insular functional connectivity in the supplementary motor area and the anterior cingulate cortex than the controls. They showed a significant correlation between left insula– supplementary motor area connectivity strength and the hyperarousal subscale of the Clinician-Administered PTSD Scale
Our findings indicate that trauma-related stimuli elicit excessive brain activation in the left insula among firefighters with PTSD
Summary
Method Twelve firefighters with PTSD and14 healthy firefighters underwent functional magnetic resonance imaging (fMRI) while performing a Stroop match-to-sample task using trauma-related photographic stimuli. A board-certified psychiatrist evaluated all participants using the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) and confirmed whether each participant met the criteria for PTSD diagnosis.[15]. Individuals who received a PDS score of 15 or higher and met the PTSD diagnostic criteria in the clinical interview were assigned to the PTSD group; 1 male participant had a high PDS score but was excluded because he did not meet the diagnostic criteria. Afterwards, the participants’ PTSD-related features were assessed according to the Clinician-Administered PTSD Scale (CAPS) through clinical interviews conducted by a psychiatrist.[16]. All participants completed a series of questionnaires after PTSD screening, including the Center for Epidemiologic Studies Depression scale (CES-D),[17] the Beck Anxiety Inventory (BAI),[18] the Alcohol Use Disorders Identification Test (AUDIT)[19] and the Pittsburgh Sleep Quality Index (PSQI).[20]. Each participant’s full-scale IQ was measured using the Wechsler Adult Intelligence Scale – Fourth Edition (WAIS-IV).[21]
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