Neural responses to emotional and neutral facial expressions in chronically violent men.

BACKGROUND: Abnormal neural responses to others' emotions, particularly cues of threat and distress, have been implicated in the development of chronic violence. We examined neural responses to several emotional cues within a prospectively identified group of chronically violent men. We also explored the association between neural responses to social emotions and psychopathic features.
METHODS: We compared neural responses to happy, sad, angry, fearful and neutral faces between chronically violent (n = 22) and nonviolent (n = 20) men using functional magnetic resonance imaging (fMRI). Participants were prospectively identified from a longitudinal study based on information collected from age 7 to 27 years. We assessed psychopathic features using a self-report measure administered in adulthood.
RESULTS: The chronically violent men exhibited significantly reduced neural responses in the dorsomedial prefrontal cortex to all faces, regardless of the emotional content, compared with nonviolent men. We also observed a hyperactive amygdala response to neutral faces in chronically violent men, but only within the context of viewing happy faces. Moreover, they exhibited a greater dorsomedial prefrontal cortex response to mildly fearful faces than nonviolent men. These abnormalities were not associated with psychopathic features in chronically violent men. LIMITATIONS: It remains unclear whether the observed neural abnormalities preceded or are a consequence of persistent violence, and these results may not generalize to chronically violent women.
CONCLUSION: Chronically violent men exhibit a reduced neural response to facial cues regardless of emotional content. It appears that chronically violent men may view emotionally ambiguous facial cues as potentially threatening and implicitly re-interpret subtle cues of fear in others so they no longer elicit a negative response.