Relief and blunted defensive conditioned responses in girls with non-suicidal self-injury behaviors

Relief is a positive emotional state that arises following the cessation of painful stimuli. Adolescents with mental health problems frequently engage in non-suicidal self-injury (NSSI). NSSI has for long been postulated as strategy for relieving intense aversive emotions. Although NSSI is hypothesized to result from a learning process, experimental evidence remains scarce. In this study, we tested whether adolescent patients suffering from NSSI have enhanced relief-learning as compared to healthy adolescents. Fifty-five girls underwent classical conditioning during which one shape (conditioned stimulus, painCS) predicted a mild painful stimulation, another shape (reliefCS) followed the pain and therefore was presented upon the moment of relief, and a third shape (CS-) was not associated with pain. Learning was quantified via physiological (startle reflex, skin conductance response) and verbal (valence, arousal and US-expectancy) responses. Adolescent patients (N: 28) did not differ in their relief-related responses to the healthy adolescents (N = 27), but they showed blunted defensive responses (lower physiological responses to painCS and no discriminative verbal responses between painCS and CS-). Relief-learning appears to be intact in adolescent patients with NSSI, whereas defensive responses during pain-learning were attenuated. Future studies should examine the impact of relief on instrumental learning to better elucidate the shift from healthy responses to persistent maladaptive instrumental behavior such as NSSI.