Abstract
There has been a growing recognition of the importance of reward processing in PTSD, yet little is known of the underlying neural networks. This study tested the predictions that (1) individuals with PTSD would display reduced responses to happy facial expressions in ventral striatal reward networks, and (2) that this reduction would be associated with emotional numbing symptoms. 23 treatment-seeking patients with Posttraumatic Stress Disorder were recruited from the treatment clinic at the Centre for Traumatic Stress Studies, Westmead Hospital, and 20 trauma-exposed controls were recruited from a community sample. We examined functional magnetic resonance imaging responses during the presentation of happy and neutral facial expressions in a passive viewing task. PTSD participants rated happy facial expression as less intense than trauma-exposed controls. Relative to controls, PTSD participants revealed lower activation to happy (-neutral) faces in ventral striatum and and a trend for reduced activation in left amygdala. A significant negative correlation was found between emotional numbing symptoms in PTSD and right ventral striatal regions after controlling for depression, anxiety and PTSD severity. This study provides initial evidence that individuals with PTSD have lower reactivity to happy facial expressions, and that lower activation in ventral striatal-limbic reward networks may be associated with symptoms of emotional numbing.
Highlights
PTSD is a complex psychiatric condition with features that extend beyond conditioned fear responses to include a wider range of emotional difficulties, such as emotional numbing [1]
PTSD group were significantly older than the Trauma Controls, and there was a trend for Trauma Controls to have longer time since trauma, but there were no significant differences in gender distribution between groups
Our hypotheses that activation in ventral striatal reward processing networks would be lower in PTSD to happy faces, and that this would be associated with emotional numbing symptoms, were largely confirmed
Summary
PTSD is a complex psychiatric condition with features that extend beyond conditioned fear responses to include a wider range of emotional difficulties, such as emotional numbing [1]. Participants with PTSD showed lower activation in nucleus accumbens and medial prefrontal cortex (mPFC) [10] and in dorsal and ventral striatal regions (caudate and putamen) [9] compared to non-trauma exposed controls in response to gains. This pattern was interpreted to reflect deficiencies in reward function. It is unclear in these studies whether the lower activation in ventral striatal regions is due to PTSD or traumaexposure, as both studies did not include a trauma-exposed control group
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