Abstract
Inconsistent findings have been found on the relation between oxytocin levels and psychopathy or callous-unemotional (CU) traits in humans, potentially because the role of trauma in oxytocin secretion and the distinction between primary and secondary psychopathy have been overlooked so far. Primary psychopathy has a stronger biological background, whereas secondary psychopathy mainly develops due to environmental adversity, such as childhood trauma. This study investigated the interaction effects of CU traits and childhood trauma on daily salivary oxytocin levels in 57 males living in residential youth care facilities. Participants provided six saliva samples (morning, afternoon, and evening for two consecutive days) and completed self-report questionnaires on CU traits and childhood trauma. A mean daily oxytocin and an oxytocin pattern across the day were examined. A significant interaction between CU traits and one trauma category (emotional neglect) on mean daily oxytocin was observed, demonstrating that subjects with high CU traits and low levels of emotional neglect (primary psychopathy) exhibited lower daily oxytocin secretion compared to subjects with high CU traits and high levels of emotional neglect (secondary psychopathy). There were no significant interactions with the other trauma types or in daily oxytocin patterns. Our findings provided a first insight into the potentially distinct oxytocin concentrations in primary and secondary psychopathy, suggesting that primary psychopathy might be linked to lower daily oxytocin output. Future longitudinal studies are required to unravel the developmental patterns of oxytocin secretion and determine whether lower oxytocin output might be a biomarker of primary psychopathy.