Context Sexual sadism is a psychiatric disorder in which sexual pleasure is derived from inflicting pain, suffering, 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 sadists relative to nonsadists would show increased responses in brain regions associated with sexual arousal (amygdala, hypothalamus, and ventral striatum) and affective pain processing (anterior cingulate and anterior insula) during pain observation.
Objective To study the neural correlates of pain observation in sadists and nonsadists.
Design Case-control cross-sectional study. Sadists and nonsadists viewed 50 social scenes, 25 that depicted a person in pain (eg, one person stabbing another person's hand with scissors) and 25 thematically matched no-pain pictures (eg, one person stabbing a table with scissors, with another person's hand nearby). Pain severity ratings (range, 0 [none] to 4 [severe]) were acquired following each picture presentation.
Setting Sand Ridge Secure Treatment Center, Mauston, Wisconsin.
Participants Fifteen violent sexual offenders, including 8 sadists and 7 nonsadists (defined using the Severe Sexual Sadism Scale) who were matched for age, IQ, and education.
Main Outcome Measures Hemodynamic response revealed by functional magnetic resonance imaging and pain severity ratings.
Results Sadists relative to nonsadists showed greater amygdala activation when viewing pain pictures. They also rated pain pictures higher on pain severity than nonsadists. Sadists but not nonsadists showed a positive correlation between pain severity ratings and activity in the anterior insula.
Conclusion These results provide neurobehavioral evidence of unusually heightened sensitivity to the pain of others in sadists.