Emotional numbing in posttraumatic stress disorder: a functional magnetic resonance imaging study.

OBJECTIVE: To explore the functional neural correlates of emotional numbing symptoms in individuals with posttraumatic stress disorder (PTSD). METHOD: The study was conducted between September 2006 and June 2008 at the University of Western Ontario. Women with (n = 14) and without (n = 16) PTSD (based on DSM-IV criteria) completed a standardized emotional imagery task while undergoing functional magnetic resonance imaging, in addition to an assessment for emotional numbing symptoms. The study design was correlational, with primary outcome measures being blood oxygenation level-dependent (BOLD) response to emotional imagery task and self-reported severity of emotional numbing symptoms. Women without PTSD were not trauma exposed. RESULTS: In women with PTSD, emotional numbing symptoms predicted less positive affect in response to positive-valence scripts (P < .05) and less BOLD response within the dorsomedial prefrontal cortex during imagery of positive and negative scripts that were explicitly socially relevant (P < .001). In contrast, in women without PTSD, emotional numbing symptoms, while unrelated to subjective emotional responses, predicted greater response within the ventromedial prefrontal cortex during positive and negative scripts, in addition to scripts that elicited fear anxiety by nonsocial means (all P values < .001). The findings could not be attributed to dysphoria. CONCLUSIONS: These findings are consistent with previous research regarding emotional numbing and emotional awareness. Less response within the medial prefrontal cortex during emotional imagery in individuals with high emotional numbing may indicate deficient conscious and reflective emotional processing. Further study is required to elucidate associations between state and trait emotional numbing and the neural correlates of psychological treatments specific to emotional numbing.