Abstract
Posttraumatic stress disorder (PTSD) is a debilitating psychiatric condition that is common in veterans returning from combat operations. While the symptoms of PTSD have been extensively characterized, the neural mechanisms that underlie PTSD are only vaguely understood. In this study, we examined the neurophysiology of PTSD using magnetoencephalography (MEG) in a sample of veterans with and without PTSD. Our primary hypothesis was that veterans with PTSD would exhibit aberrant activity across multiple brain networks, especially those involving medial temporal and frontal regions. To this end, we examined a total of 51 USA combat veterans with a battery of clinical interviews and tests. Thirty-one of the combat veterans met diagnostic criteria for PTSD and the remaining 20 did not have PTSD. All participants then underwent high-density MEG during an eyes-closed resting-state task, and the resulting data were analyzed using a Bayesian image reconstruction method. Our results indicated that veterans with PTSD had significantly stronger neural activity in prefrontal, sensorimotor and temporal areas compared to those without PTSD. Veterans with PTSD also exhibited significantly stronger activity in the bilateral amygdalae, parahippocampal and hippocampal regions. Conversely, healthy veterans had stronger neural activity in the bilateral occipital cortices relative to veterans with PTSD. In conclusion, these data suggest that veterans with PTSD exhibit aberrant neural activation in multiple cortical areas, as well as medial temporal structures implicated in affective processing.
Highlights
Posttraumatic stress disorder (PTSD) is a psychiatric disorder involving re-experiencing, avoidance, negative mood and cognition and arousal symptoms (American Psychiatric Association, 2013)
We examined a group of combat veterans with and without PTSD using resting-state MEG and clinical assessments
Eleven veterans with PTSD were on stable doses of psychiatric medication (4 SSRIs, 3 benzodiazepines and 4 mood stabilizers), and the other 20 veterans with PTSD were not taking any psychiatric medication
Summary
Posttraumatic stress disorder (PTSD) is a psychiatric disorder involving re-experiencing, avoidance, negative mood and cognition and arousal symptoms (American Psychiatric Association, 2013). Previous fMRI and PET studies of PTSD have consistently reported aberrant activation in the anterior, middle and posterior cingulate cortices, medial prefrontal and middle frontal gyri, as well as the insula and medial temporal structures such as the hippocampus and amygdalae of patients with PTSD relative to matched controls (Rabinak et al, 2011; Morey et al, 2012; Pitman et al, 2012; Sripada et al, 2012; Boccia et al, 2016). Structural studies have reported reduced volume in similar regions, including the hippocampal (O’Doherty et al, 2015) and ACC in patients with PTSD relative to controls (Meng et al, 2014; O’Doherty et al, 2015). It seems unlikely that the disorder can be uniquely attributed to dysfunction in the fronto-limbic regions that have been historically implicated
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