This study aimed to explore which factors had a greater impact on substance craving in people with substance use and the direction of the impact. A total of 895 male substance users completed questionnaires regarding substance craving, psychological security, positive psychological capital, interpersonal trust, alexithymia, impulsivity, parental conflict, aggression behavior, life events, family intimacy, and deviant peers. Calculating the factor importance by gradient boosting method (GBM), found that the psychosocial factors that had a greater impact on substance craving were, in order, life events, aggression behavior, positive psychological capital, interpersonal trust, psychological security, impulsivity, alexithymia, family intimacy, parental conflict, and deviant peers. Correlation analysis showed that life events, positive psychological capital, interpersonal trust, psychological security, and family intimacy negatively predicted substance craving, while aggression behavior, impulsivity, alexithymia, parental conflict, and deviant peers positively predicted substance cravings. These findings have important implications for the prevention and intervention of substance craving behavior among substance users.

Persons who are addicted are known to show cue-induced responses (such as psychological craving) to drug-related cues. Previous research showed that both tool-related (e.g., syringe) and action-related (e.g., use of the syringe) drug cues can elicit craving. However, whether the two types of drug related cues can elicit the same brain reactivity and similar degree of disinhibition is still unclear, especially because of the scarcity of ERP studies on this topic. Using a behavioral task and the ERP technique, the present study investigated the behavior reactivity and EEG characteristics shown by men addicted to heroin and healthy controls in response to tool-related and action-related drug cues.Participants were 36 men, 19 of whom were addicted to heroin and 17 of whom were healthy non-drug users, matched on age and years of education. Participants engaged in the two-choice Oddball task, which included two conditions: A. the tool condition, with a picture of a "cup" serving as the standard stimulus and pictures of drug-use tools serving as deviant stimuli; B. the action condition, with a picture of "drinking water" serving as the standard stimulus and pictures of drug-use actions serving as deviant stimuli. In this experiment, the probabilities of standard stimuli and deviant stimuli were 70% and 30%. Participants were asked to press different keys on the keyboard in response to standard stimuli and deviant stimuli as rapidly and accurately as possible.Behavioral results indicated that in men who were addicted to heroin, greater disinhibition was seen in a longer reaction time in response to action cues than tool cues. Between-group analyses of the ERP data showed that compared to the healthy controls, men who were addicted to heroin demonstrated a smaller N2 and larger P3 amplitude in response to drug related cues. Moreover, action cues elicited a smaller N2 amplitude in the heroin addicted group than the control group, especially in the frontal, central and central-parietal areas of the brain, and a larger P3 amplitude, especially in the central and parietal areas of the brain. Within-group analyses in just the heroin addicted group showed that the N2 was smaller in response to action cues versus tool cues. Meanwhile, the action cues elicited a larger amplitude of P3 than the tool cues, especially in the central, central-parietal and parietal regions of the brain.These findings provide behavioral and ERP evidence for the hypothesis that different types of drug-related cues produce different cue-induced reactivity. More specifically, drug use action stimuli, which appear to trigger greater disinhibition and greater ERP reactivity in the brain areas associated with motor resonance, should be considered in the treatment of addiction and in relapse prevention.

Empathy for pain, the ability to share and understand the pain of others, plays an important role in the survival and development of individuals. Previous studies have found that social pain experience affects empathy for pain, but potential gender differences have not been considered. The stage of information processing during which gender is most likely to play a moderating role has yet to be clarified. In the current study, we set up two groups (social pain experience priming: social exclusion group; positive social interaction experience priming: social inclusion group) with a Cyberball game paradigm. We recorded the electrophysiological responses when participants were completing an empathy task. An early frontal P2 and N2 differentiation between painful stimuli and neutral stimuli was observed and females showed larger P2 amplitudes than males. At the P3 stage, in the social exclusion group, males showed similar parietal P3 amplitudes for painful and neutral stimuli, while females showed smaller P3 amplitudes for painful stimuli. At the central-parietal late positive potential (LPP) stage, females in the social inclusion group showed larger LPP amplitudes for painful stimuli than males. Our results suggest that gender plays a significant moderating role in how social pain experience affects empathy for pain during the late cognitive processing stage. Experiment 2 was designed to investigate the cognitive mechanism behind the results for the P3 component in females and the results partially confirmed our speculation. This study provides a neurophysiological basis for the dynamic gender differences in the effects of social pain experience on empathy for pain.Keywords Social pain • Gender • Empathy for pain • Event-related potentials (ERP)

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