Context
Sexual sadism is a psychiatric disorder in which sexual pleasure is derived from inflicting pain, suffering, and/or humiliation on others. While the psychological and forensic aspects of sexual sadism have been well-characterized, little is known about the neurocognitive circuitry associated with the disorder. Sexual sadists show increased peripheral sexual arousal when observing other individuals in pain. The neural mechanisms underlying this unusual response are not well understood. We predicted that sexual sadists, relative to non-sadists, would show increased responses in brain regions associated with sexual arousal (amygdala, hypothalamus, ventral striatum) and affective pain processing (anterior cingulate, anterior insula) during pain observation.
Objective
To study the neural correlates of pain observation in sexual sadists and non-sadists.
Design
Case-control, cross-sectional study. Sexual sadists and non-sadists viewed 50 social scenes, 25 which depicted a person in pain (e.g., one person stabbing another person’s hand with scissors) and 25 thematically matched no-pain pictures (e.g., one person stabbing a table with scissors with another person’s hand nearby). Pain severity ratings (0 = none, 4 = severe) were acquired following each picture presentation.
Setting
Sand Ridge Secure Treatment Center, Mauston, Wisconsin.
Participants
15 violent sexual offenders; eight sexual sadists and seven age, IQ, and education-matched non-sadists (defined by the Severe Sexual Sadism Scale).
Main Outcome Measures
Hemodynamic response revealed by functional magnetic resonance imaging (fMRI), and pain severity ratings.
Results
Sexual sadists, relative to non-sadists, showed greater amygdala activation when viewing pain pictures. They also rated pain pictures higher on pain severity than non-sadists. Sexual sadists, but not non-sadists, showed a positive correlation between pain severity ratings and activity in the anterior insula.
Conclusions
These results provide neurobehavioral evidence of unusually heightened sensitivity to the pain of others in sexual sadists.