In this study, we delved into the impact of substance use and problematic internet use on young individuals' multiple injuries. This is the first study in China to emphasize the differences in injuries associated with the co-occurrence of both SU and PIU compared to normal young adults. In addition, this study explored the impact of psychological and social factors associated with substance and internet use (i.e., mental health, childhood trauma, and peer bullying) on intentional injuries in young adults in China. These findings are instructive for reducing the incidence of injuries in China, particularly in emerging adults.
Comparison of Demographics, Psychological, Social Factors On Injuries Among Substance Use and Problematic Internet Use Group
We categorized substance users into low-, medium-, and high-risk groups based on assessment scales and categorized participants into a non-PIU group, a mild-moderate PIU group, and a severe PIU group based on the severity of the Internet Addiction Test (IAT). We found that individuals with medium- and high-risk SU exhibited greater mean age, urban area background, and single-parent family status than did individuals in the low-risk group. These characteristics could be influenced by several factors. A high average age may indicate that a group is more likely to be exposed to a variety of different types of substances26. Additionally, upperclass members might face the challenges of employment pressure and future uncertainty27, factors that have been linked to EA' substance use and increase use28. Urban areas provide easier access to illicit materials29. A single-parent family could lead to weakened social support systems, and low incomes could disrupt the level of normative supervision and support for single parents, which increase a child's risk of SU30. Certain family structures might result in adolescents experiencing higher levels of distress and negative consequences. These factors included residential mobility; changes in parenting styles; and biological relationships, such as parental remarriage and general social unrest31, 32. Substance use is often used as a coping or avoidance mechanism when adolescents experience distress, anxiety, and negative emotions33, 34.
In terms of problematic internet use, individuals in the PIU group demonstrated significant differences in sexual orientation, gender identity, sleep quality, and personality traits. In reality, discrimination based on sexual orientation and gender identity manifests in several ways, including verbal harassment, employment discrimination, and physical violence 35. This made them more prone to PIU behaviors. Indulgence in virtual Internet environments can lead to social isolation, especially for sexual minorities, and may increase individuals’ identity anxiety and social stress online36. Decreased sleep quality could be associated with excessive participation in online activities at night, which in turn negatively affects one’s biological clock and mental health 37. In addition, we investigated personality traits in depth and found that individuals in the heavy PIU group were more likely to have higher levels of stress, neuroticism, extroversion, openness, agreeableness, and conscientiousness. This provided important clues for understanding the association between PIU and individual psychological traits. Emerging adults might feel uncomfortable in real life due to negative emotions and low self-esteem and, in turn, might seek virtual environments as an escape mechanism. They spend more time addicting to the internet and developing behavioral patterns that are closely tied to the internet, all of which affect their personality traits, especially neuroticism38.
Risk of Injuries in Substance Use, Problematic Internet Use, and Comorbid Groups
In terms of injury outcomes, our study further revealed the serious impact of substance use and problematic internet use on an individual's health. Individuals in the SU or PIU subgroup were more likely to experience NSSI and suicidal ideation than were individuals in the low-SU and non-PIU subgroups. This finding reflected the independent negative effects of SU and PIU on mental health. Substance use could have direct effects on individuals through physiological and pharmacological pathways; e.g., alcohol consumption, tobacco use, and other SU behaviors impair psychological and neurocognitive development and increase the risk of academic failure, chronic disease, and psychiatric disorders39, 40. PIU might promote suicidal ideation by triggering mental health problems 41, such as anxiety and depression, through dependence on cognitive and emotional dimensions 42. Furthermore, it was of interest that individuals with both SU and PIU more prominently exhibited a risk for unintentional injury, NSSI and suicidal ideation. This finding reflected a positive correlation between these two issues, consistent with previous findings43, 44. Initial SU and multiple SU were more likely to increase the risk of PIU45. This might be because individuals with SU and PIU share similar vulnerable brain regions, including the dorsolateral and orbitofrontal cortices46, 47. Similarly, PIU was found to be a significant predictor of SU and included smoking, alcohol use, and drug use48. All of these factors increase the likelihood of injury.
Factors influencing injuries in SU, PIU, and Comorbid Groups
Based on the results of the aforementioned injuries, we further explored factors associated with intentional injuries within the affected population. Numerous factors were closely linked to NSSI and suicidal ideation, but their impact varied among different demographic groups. In summary, psychological conditions, neuroticism, and residing in urban areas were found to be associated with NSSI and suicidal ideation across multiple populations. Poor sleep quality showed a positive correlation with the occurrence of suicidal ideation. Additionally, age, gender, stress, peer bullying, and openness also influenced these variables49. In conclusion, improving the mental health of young people, the quality of their sleep, appropriate stress release and the control of bullying in schools may play a significant role in the occurrence of intentional injuries. Furthermore, it is even more important to intervene with emerging adulthood who are younger, live in urban areas, have neurotic personalities and female groups.
For NSSI behaviors, high neuroticism scores were strongly associated with the development of NSSI in the PIU population. Neuroticism, one of the Big Five personality traits, is a partially heritable personality trait that includes negative affect50 and increased sensitivity to stress51. Highly neurotic individuals might avoid or mitigate unpleasant and disgusting emotional experiences to some extent by resorting to NSSI behaviors52. Positive associations between high SCL and NSSI have been found in several populations. This reflected the strong link between mental health and self-injury. Emerging adults lacked effective coping strategies for dealing with negative emotions and were more likely to seek relief through NSSI behaviors. This could lead to more serious psychological and social consequences (shame, guilt) and self-criticism, which can lead to damaged social relationships and negative emotions, creating a vicious cycle53. Among the IAT and comorbid groups, we found that emerging adults living in rural areas were less prone to NSSI behaviors than were those living in urban areas. This might be because urban EA have a heavier academic load, higher parental expectations, and encounter a variety of pressures as individuals evolve54. As a result, individuals are prone to various psychological problems, including serious mental disorders, which means that NSSI behaviors are more likely to occur55. In addition, we also observed a negative correlation between this protective effect and suicidal ideation in a comorbid population.
This was followed by a discussion of the impact of suicidal ideation in different populations. Among those in the SU population, emerging adults who experienced peer bullying were more likely to experience suicidal ideation. Patients typically report higher levels of negative health outcomes such as depression, anxiety, and other internalizing behaviors56. Older students were less likely to report suicidal ideation than younger students were. This finding was consistent with previous research57 and could be attributed to the more developed problem-solving skills of upperclassmen. Relative to underclasses, they might solve problems in a more rational, less impulsive, and destructive manner 58. In the PIU population, we found that stress was associated with the development of suicidal ideation. Stress leads to long-term changes in brain morphology and biology, which include alterations in the functional status of various neurotransmitters59 and in interneuronal signaling systems, which could lead to suicidal ideation60. There was a negative correlation between individuals' greater openness to experience and suicidal ideation. This finding suggested that individuals with higher levels of openness might be more positive in terms of their mental health. Openness is generally considered to be a positive personality trait that represents greater acceptance of novelty, creativity, and change61. Individuals with high openness were more likely to experience positive emotions and were more sensitive to good things in life. This approach helps to alleviate negative emotions and reduce the risk of suicidal ideation62. Among those with comorbidities, females were more likely to have suicidal ideation, consistent with the results of related studies63. This might be because women are more submissive, psychologically sensitive57 and more prone to experience symptoms of depression and anxiety64 than men are, which in turn increases the risk of suicidal ideation65. In addition, females were more inclined to submit to the school system and experienced greater academic stress, further increasing the risk of suicidal ideation66.
Associations between poor mental health, neuroticism, poor sleep quality, and suicidal ideation have been found in multiple populations. Numerous studies have shown that a greater burden of depression and anxiety symptoms is associated with a greater risk of suicidal ideation 37, 67. The neuroticism association could reflect the influence of emotional stability on suicidal ideation 68. Highly neurotic individuals tended to have low emotional regulation and were poor at seeking help from outside sources; therefore, they were prone to increased depression 69. In addition, the association between neuroticism and psychological states might involve complex interactions that collectively influence the development of suicidal ideation70. Poor sleep quality is one of the most important predictors of suicidal ideation71. One possible explanation was that poor sleep quality led to nighttime wakefulness, which could result in decreased frontal lobe function. Decreased frontal lobe function might lead to decreased problem solving and increased impulsive behavior, both of which could be associated with suicide risk72. Another possibility is that insomnia or nightmares may trigger perceptions of failure, which in turn leads to feelings of entrapment, isolation, despair, and ultimately suicide73.
Strengths and limitations
To the best of our knowledge, this is the first analysis to examine the association of substance use, problematic internet use, and comorbidity with the multiple injuries among Chinese emerging adulthood. In addition, the study examined the factors influencing injuries in different populations. This study has several limitations. First, all of our surveys relied on self-reported data from students. Second, there may be concealment or underestimation of problematic internet use and substance use due to social expectations, self-presentation, and privacy protection. Third, the cross-sectional research design of this study did not confirm causal relationships between substance use, problematic internet use, and injury. Fourth, the broad applicability and representativeness of the findings may be somewhat limited because we relied on data from only two universities. This may lead to uncertainty about the applicability of our findings to different populations, different universities, or different regions of the student body.