Non-suicidal self-harm is linked to suicidal thoughts in Chinese adolescents with mood disorders: a cross-sectional report

Non-suicidal self-harm is linked to suicidal thoughts in Chinese adolescents with mood disorders: a cross-sectional report 中国青少年心境障碍患者非自杀性自伤与自杀观念的关联性：一项横断面研究 1 2 equal first-author 1 3 4 5 equal 1 3 4 5 6 7 8 1 3 4 5 corresp equal Shaohua HU, dorhushaohua@zju.edu.cn Shaohua HU, dorhushaohua@zju.edu.cn dorhushaohua@zju.edu.cn https://orcid.org/0000-0003-0570-670X Department of Psychiatry, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou310003, China Department of Psychiatry, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou310003, China Shanghai Pinghe Bilingual School, Shanghai201206, China Shanghai Pinghe Bilingual School, Shanghai201206, China The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou310003, China The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou310003, China Brain Research Institute of Zhejiang University, Hangzhou310003, China Brain Research Institute of Zhejiang University, Hangzhou310003, China Zhejiang Engineering Center for Mathematical Mental Health, Hangzhou310003, China Zhejiang Engineering Center for Mathematical Mental Health, Hangzhou310003, China Department of Rehabilitation, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou310003, China Department of Rehabilitation, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou310003, China Research Center for Clinical Pharmacy, State Key Laboratory for Diagnosis and Treatment of Infectious Disease, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou310003, China Research Center for Clinical Pharmacy, State Key Laboratory for Diagnosis and Treatment of Infectious Disease, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou310003, China Provincial Key Laboratory for Drug Evaluation and Clinical Research, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou310003, China Provincial Key Laboratory for Drug Evaluation and Clinical Research, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou310003, China 目的 2 非自杀性自伤在青少年群体中很常见，中国对青少年自伤问题的关注仍不充分。本研究通过对青少年及其父母的问卷调查，探讨了青少年的自伤行为，及其与家庭、学业、情绪和自杀因素的关系。 方法 2 所有受试者均来自浙江大学医学院第一附属医院精神科。根据《精神障碍诊断与统计手册》第五版（DSM-5）的诊断标准，纳入诊断为重度抑郁障碍或双相情感障碍的青少年及其父母。共有70名青少年和59名家长参加了这项研究。研究人员收集了青少年自伤的人口学特征和相关信息，包括患者和家长报告的数据。采用斯皮尔曼秩相关分析计算自伤与其他因素的相关性。 结果 2 受试的青少年平均年龄为（16.1±2.4）岁。在有非自杀性自伤行为的青少年中，女性占35例（79.5%）。受试青少年中，38人（54.3%）报告了调查前一个月内的自伤行为，26人（37.1%）报告了在过去一年内5次以上的自伤行为，以上两项父母报告的数据分别为11人（18.6%）和4人（6.8%）。有绝望感（68.6%）、希望死亡（62.9%）、自杀念头（70.0%）以及希望意外结束生命（62.9%）想法的青少年比例较高，而父母报告的上述情绪障碍比例相对较低，分别为37.3%、23.7%、6.8%和11.9%。在与非自杀性自伤相关的因素中，不良的家庭关系、学习压力和情感问题如"悲伤时无人倾诉"、"心理痛苦无法理解"等，在受试青少年和家长的报告中都普遍存在。青少年报告的与"一个月内自伤行为"呈正相关的因素包括"绝望感"、"自杀念头"、"希望意外结束生命"和"由于预期中的死亡匆忙处理事务"（ ρ 分别为0.429、0.463、0.482和0.483，所有 P < 0.05）。值得注意的是，"希望死亡"和"希望意外结束生命"（ ρ 分别为0.407和0.407，所有 P < 0.05）也是"过去一年中自伤5次以上"的强正相关因素。在家长报告中，"绝望感"是唯一和"一个月内自伤行为"呈正相关的因素（ ρ =0.261， P < 0.05）。 结论 2 有心境障碍的中国青少年实行非自杀性自伤行为的风险较高，且与自杀观念呈正相关。有非自杀性自伤的青少年的父母可能低估了这种情况，需要更重视这方面的情况。 非自杀性自伤 青少年 家长 心境障碍 Non-suicidal self-injury (NSSI) refers to any intentional, self-inflicted behavior that causes direct damage to body tissues ( Kerr et al., 2010 Kerr et al., 2010 ), and has emerged as a challenging public health issue worldwide, especially among adolescents. The most common presentations of NSSI include skin-cutting, severe scratching, and burning ( Whitlock et al., 2006 Whitlock et al., 2006 ). In a community-based study conducted in England, 6% of 5506 adolescents reported self-harm in 2014, and 1320 adolescents (74% aged 15‒17 years) presented to hospitals due to non-fatal self-harm ( Geulayov et al., 2018 Geulayov et al., 2018 ). In Australia, 8% of adolescents aged less than 20 years reported a history of self-harm ( Hiscock et al., 2018 Hiscock et al., 2018 ). In addition, the prevalence of NSSI has significantly increased in recent years. It was reported by McManus et al. (2019) McManus et al. (2019) that the prevalence of self-reported lifetime NSSI increased from 2.4% in 2000 to 6.4% in 2014, with the largest increase in females aged 16–24 years (from 6.5% to 19.7%). Researchers have also proposed an "iceberg" model of self-harm, indicating that the phenomenon of NSSI is often concealed and that most individuals with NSSI do not seek help from others ( McMahon et al., 2014 McMahon et al., 2014 ; Geulayov et al., 2018 Geulayov et al., 2018 ). The outcomes of NSSI may not be as notable as suicide; however, NSSI is still an issue of critical importance due to its association with a variety of adverse consequences, including suicidal thoughts and suicide attempts. Children and adolescents who committed NSSI were approximately nine times more likely to subsequently die unnaturally, with increased risks of suicide and fatal acute alcohol or drug poisoning ( Morgan et al., 2017 Morgan et al., 2017 ). Other studies have also shown a strong positive correlation between future suicide attempts and NSSI, which was measured by form and frequency ( Guan et al., 2012 Guan et al., 2012 ; Hamza et al., 2012 Hamza et al., 2012 ; Mars et al., 2019 Mars et al., 2019 ). It is estimated that approximately 800 000 people die by suicide every year ( World Health Organization, 2019 World Health Organization, 2019 ), and suicide has become one of the leading causes of death in adolescents. With regard to long-term outcomes, Borschmann et al. (2017) Borschmann et al. (2017) suggested that mental health problems, daily tobacco smoking, and illicit drug use and dependence were all more common among adolescents with NSSI. NSSI can occur either concurrently with mental disorders, such as depression ( Moran et al., 2012 Moran et al., 2012 ), or without a comorbid diagnosis of mental disorders ( Nock et al., 2006 Nock et al., 2006 ; Glenn and Klonsky, 2013 Glenn and Klonsky, 2013 ). NSSI has recently become a major mental health problem in many countries, including China. A previous study reported that 33.6% of 3161 Chinese adolescents were involved in certain forms of NSSI ( Tang et al., 2013 Tang et al., 2013 ). Adolescent NSSI is an indicator of future adverse individual health and social outcomes throughout adulthood ( Borschmann et al., 2017 Borschmann et al., 2017 ). However, NSSI in adolescents has received inadequate attention from health services and national health organizations. More than 50% of respondents who reported lifetime NSSI did not seek mental health services or psychological support ( McManus et al., 2019 McManus et al., 2019 ). Many studies have been conducted to identify the risk factors related to suicidal behavior, such as personality and individual differences, cognitive factors, social aspects, and negative life events ( Hamza et al., 2012 Hamza et al., 2012 ; O'Connor and Nock, 2014 O'Connor and Nock, 2014 ). However, factors that influence the behavior of NSSI are still unclear. McManus et al. (2019) McManus et al. (2019) indicated that the intention of dealing with negative emotions (including anger, tension, anxiety, and depressive mood) was associated with NSSI. Huang and Zhang (2016) Huang and Zhang (2016) found that emotional adjustments, drug dependence, neuroticism, and the parents' relationship may be associated with NSSI in college students, and NSSI clustering at class level might also be involved. Fox et al. (2015) Fox et al. (2015) proposed that a prior history of NSSI, Cluster B personality, and hopelessness were the strongest risk factors found in current studies regarding NSSI. Depressive symptoms were also found to be a significant predictor of future NSSI. Other factors, such as self-injurious behavior in peers, may also have an impact on NSSI in adolescents ( Prinstein et al., 2010 Prinstein et al., 2010 ). Several studies have demonstrated that a significant proportion of individuals engaging in NSSI reported feeling better after harming themselves ( Franklin et al., 2010 Franklin et al., 2010 ; Weinberg and Klonsky, 2012 Weinberg and Klonsky, 2012 ; Bresin and Gordon, 2013 Bresin and Gordon, 2013 ). However, few studies have examined other potential risk factors of NSSI in adolescence, especially in non-western countries. A longitudinal study of 5154 Chinese adolescents found that previous exposure to suicide-death or suicidal behaviors of relatives were correlated with increased risk of NSSI ( Liu et al., 2019 Liu et al., 2019 ). Despite the increasing number of studies on NSSI, few studies have investigated the prevalence of NSSI in patients with mood disorders. Therefore, the aim of the current study was to address the issue of NSSI in Chinese adolescents with mood disorders. Herein, a cross-sectional survey of adolescents with mood disorders and their parents was performed to identify the relationship between NSSI and family, academic, emotional, and suicidal factors. The study was carried out from July 1 to Sept. 31, 2019. Participants were recruited from the psychiatric clinic or wards of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China. Adolescents with a previous or current diagnosis of major depressive disorder or bipolar disorder according to the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5), and their parents, were eligible to participate in this study. Demographic profiles, including age, gender, educational level, marital status of parents, siblings, and religious belief, were recorded. A total of 70 adolescents and 59 parents completed the questionnaire in this study. Of these participants, 55 adolescents and their parents were matched. Demographic data of the adolescents, but not their parents, are shown in Table 1 Table 1 . The average age of the adolescents was (16.1±2.4) years, and the proportion of females was 71.4%. Most (86.7%) were at a middle school (junior or senior) educational level. Only a minority of adolescents (14.3%) had a religious belief. With regard to their family background, 17.1% of the adolescents' parents were divorced, and nearly half of the adolescents (48.6%) had siblings. Data are expressed as number (percentage) of adolescents or mean±standard deviation. NSSI: non-suicidal self-injury. Variables All adolescents ( n =70) Adolescents with NSSI ( n =44) Sex Male 20 (28.6%) 9 (20.5%) Female 50 (71.4%) 35 (79.5%) Age (year) 16.1±2.4 17.0±2.7 12 1 (1.4%) 0 (0%) 13‒15 30 (42.9%) 22 (50.0%) 16‒18 31 (44.3%) 17 (38.6%) 19‒20 5 (7.1%) 4 (9.1%) 21‒25 3 (4.3%) 1 (2.3%) Education Primary school 2 (2.9%) 1 (2.3%) Junior middle school 27 (38.6%) 16 (36.6%) Senior middle school 33 (47.1%) 18 (40.9%) College/university 8 (11.4%) 7 (20.2%) Marital status of parents Divorced 12 (17.1%) 8 (18.2%) Married 58 (82.9%) 36 (81.8%) Family members/siblings No siblings 36 (51.4%) 24 (54.5%) Have siblings 34 (48.6%) 20 (45.5%) Religious belief No 60 (85.7%) 40 (90.9%) Yes 10 (14.3%) 4 (9.1%) Two versions of a questionnaire evaluating self-injury behavior (NSSI in the last month, and/or NSSI more than five times in the last year) and associated factors in the adolescents and their parents were administered (see supplementary information: self-injury questionnaire (adolescent version) and self-injury questionnaire (parent version)). Potential factors linked to self-injury behaviors, including predisposition, family financial status, parents' relationship, relationship with others, history of bullying, and suicidal ideations or plans, were investigated in this study. Data analysis was performed using SPSS 20.0 (IBM Corp., Armonk, New York, USA). Normally distributed measurement data are presented as mean±standard deviation (SD) or as median (interquartile range). Enumeration data are presented as frequency or percentage (%). Spearman's rank correlation analysis was performed to calculate the correlation between different factors. P < 0.05 was considered statistically significant. Of the adolescents included, 44 (62.9%) reported NSSI. Of the adolescents with NSSI, 35 (79.5%) were female and 39 (88.6%) were aged 13 to 18 years. In the adolescents included, 38 (54.3%) reported NSSI in the month prior to the survey, and 26 (37.1%) reported NSSI more than five times in the last year before this survey (the frequency and duration criterion of the diagnosis of NSSI Disorder in DSM-5). Of note, 20 (28.6%) of the participants had committed self-harm both in the last month and more than five times in the last year. However, only 11 (18.6%) and 4 (6.8%) parents reported the above two situations in their children, respectively. According to the 70 adolescents, 48 (68.6%) reported hopelessness; 44 (62.9%) reported a wish to die; 49 (70.0%) reported suicidal thoughts; 44 (62.9%) reported a wish to end life by accident. However, the proportions of the above mood disorders reported by their parents were extremely low, accounting for 37.3%, 23.7%, 6.8%, and 11.9%, respectively ( Table 2 Table 2 ). NSSI: non-suicidal self-injury. 2 Consequence 2 Percentage in total sample (%) Self-report( n =70) Parent report( n =59) Hopelessness 68.6 37.3 Wish for death 62.9 23.7 Having the ability and courage to commit suicide 24.3 17.0 Suicidal ideations 70.0 (21.4% with detailed plans) 6.8 (1.7% with detailed plans) Suicidal plans Cutting wrists 10.0 Jumping building 5.7 1.7 Charcoal-burning 2.9 Hanging 2.9 Drugs 2.9 Electrocution 1.4 Detailed suicidal plans with enough determination to implement 17.1 1.7 Wish to end life by accidents 62.9 11.9 Handle things in a hurry due to anticipation of death 18.6 1.7 Among the listed family factors, 34 (48.6%) adolescents and 21 (30.0%) parents reported poor family relationships. Among the academic factors, "failing the exams recently," "too much academic pressure from expectations of parents or teachers," and "limited time for leisure or entertainment due to large amounts of schoolwork," appeared to be the major reasons. Among the emotional factors, problems such as "having nobody to talk with when feeling sad" and "psychological pain cannot be understood" were common and similarly reported by the adolescents and their parents ( Table 3 Table 3 ). NSSI: non-suicidal self-injury. 2 Variables 2 Percentage in the total sample (%) Self-report ( n =70) Parent-report ( n =59) 3 Family Feeling that life was not worth living due to poor family relationship 48.6 20.3 Family financial burden 7.1 5.1 Death of close relatives recently 4.3 1.7 Falling seriously ill recently (yourself or relatives) 4.3 1.7 3 Academic Failing exams recently 30.0 23.7 Pressure due to high school or university entrance test 17.1 15.3 Too much academic pressure from expectations of parents or teachers 45.7 54.2 Limited time for leisure or entertainment due to large amount of schoolwork 38.6 42.4 Strained relationship with schoolfellow or friends 11.4 15.3 Suffered from bullying 12.9 37.3 Feeling embarrassed or ashamed due to family financial burden 8.6 10.1 3 Emotion Have nobody to talk to when feeling sad 70.0 57.6 Psychological pain cannot be understood 75.7 66.1 3 Others Accidental fright or incident 7.1 5.1 To better clarify the relationships between different factors, rank correlation analysis was performed. As shown in Tables 4 4 and 5 5 , a positive correlation was identified between "self-harm in the last month" and "over five incidents of NSSI in the past year," as reported by both adolescents and parents (correlation coefficient ρ‍ =0.349, P < 0.05; ρ‍ =0.390, P < 0.05). As reported by the adolescents, other factors positively correlated with "self-harm in the last month" included "hopelessness," "wish for death," "suicidal ideations," "detailed suicide plans," "wish to end life by accident," "handle things in a hurry due to anticipation of death," and "feeling embarrassed or ashamed due to family financial burden" ( ρ‍ =0.429, 0.363, 0.463, 0.265, 0.482, 0.483, and 0.281, respectively, all P < 0.05). Of note, factors such as "hopelessness," "wish for death," "suicidal ideations," "wish to end life by accident," and "handle things in a hurry due to anticipation of death" ( ρ‍ =0.329, 0.407, 0.374, 0.407, and 0.241, respectively, all P < 0.05) were also positively correlated with "over five times of NSSI in the past year." In addition, "too much academic pressure due to expectations of parents or teachers" and "feeling that life was not worth living due to poor family relationships" were factors positively associated with "over five incidents of NSSI in the past year" ( ρ =0.244 and 0.318, respectively, both P < 0.05; Table 4 Table 4 ). However, as reported by the parents, "hopelessness" was the only factor positively associated with "self-harm in the last month" ( ρ =0.261, P < 0.05; Table 5 Table 5 ). A1: self-harm in the last month; A2: over five times of NSSI in the past year; A3: hopelessness; A4: wish for death; A5: self-certainty of ability and courage to commit suicide; A6: suicidal ideations; A7: detailed suicide plans; A8: wish to end life by accidents; A9: handle things in a hurry due to anticipation of death; A10: have nobody to talk to when feeling sad; A11: psychological pain cannot be understood; A12: limited time for leisure or entertainment due to large amount of schoolwork; A13: too much academic pressure due to expectations of parents or teachers; A14: feeling that life was not worth living due to poor family relationship; A15: suffer from bullying; A16: feeling embarrassed or ashamed due to family financial burden; A17: temporarily absent from school. Answer “Yes” was defined as 1, while “No” was defined as 2 (see supplementary information: self-injury questionnaire (adolescent version) and self-injury questionnaire (parent version)). * Statistical significance is set at P < 0.05. Factor A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A1 1.000 A2 0.349 * 1.000 A3 0.429 * 0.329 * 1.000 A4 0.363 * 0.407 * 0.690 * 1.000 A5 -0.015 0.116 0.096 0.229 1.000 A6 0.463 * 0.374 * 0.430 * 0.400 * 0.225 1.000 A7 0.265 * 0.121 0.226 0.271 * 0.273 * 0.298 * 1.000 A8 0.482 * 0.407 * 0.626 * 0.755 * 0.160 0.465 * 0.350 * 1.000 A9 0.438 * 0.241 * 0.165 0.291 * 0.072 0.232 0.465 * 0.367 * 1.000 A10 0.088 -0.142 0.228 0.013 -0.165 0.184 0.215 0.077 0.072 1.000 A11 0.216 0.160 0.550 * 0.392 * 0.010 0.284 * 0.169 0.461 * 0.099 0.502 1.000 A12 0.020 0.120 0.284 * 0.305 * 0.030 0.006 0.029 0.184 -0.227 0.134 0.312 * 1.000 A13 0.209 0.244 * 0.251 * 0.290 * 0.149 0.225 0.115 0.290 * 0.152 0.038 0.252 0.333 * 1.000 A14 0.203 0.318 * 0.289 * 0.392 * 0.183 0.262 * 0.316 * 0.274 * 0.271 * 0.200 0.284 * 0.111 0.141 1.000 A15 0.095 -0.119 -0.108 -0.058 0.081 0.158 0.052 0.119 -0.074 0.251 * 0.118 0.134 0.162 0.054 1.000 A16 0.281 * -0.024 0.097 0.024 0.184 0.089 0.132 0.130 0.116 0.200 0.173 0.072 0.334 * 0.213 0.340 * 1.000 A17 0.081 -0.114 -0.024 -0.089 0.277 * -0.043 0.166 -0.021 0.055 0.100 -0.048 0.004 0.051 -0.245 * 0.165 0.170 1.000 The definitions of different factors (A1‒A17) are consistent with those in Table 4. * Statistical significance is set at P < 0.05. Factor A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A1 1.000 A2 0.390 * 1.000 A3 0.261 * 0.210 1.000 A4 0.244 0.008 0.641 * 1.000 A5 0.132 0.238 0.492 * 0.385 * 1.000 A6 0.217 0.195 0.350 * 0.325 * 0.238 1.000 A7 -0.063 -0.035 0.170 0.235 0.291 * -0.035 1.000 A8 0.094 -0.099 0.367 * 0.411 * 0.114 0.318 * -0.048 1.000 A9 -0.063 -0.035 0.170 0.235 -0.059 -0.035 -0.017 0.358 * 1.000 A10 -0.118 -0.178 0.213 0.572 0.600 0.177 0.247 0.113 0.396 1.000 A11 -0.117 0.051 0.330 * 0.147 0.228 0.051 0.094 0.152 0.094 0.763 1.000 A12 0.030 0.042 0.119 0.086 0.161 0.042 -0.113 0.110 0.153 -0.167 -0.111 1.000 A13 0.003 0.112 0.005 -0.047 0.052 -0.023 -0.143 0.127 0.121 -0.030 -0.011 0.306 * 1.000 A14 0.082 0.199 0.220 0.213 0.108 0.366 * -0.066 0.205 0.260 * 0.092 0.184 -0.007 0.295 * 1.000 A15 0.081 -0.069 0.203 0.311 * 0.119 0.210 -0.101 0.151 0.170 0.023 0.034 0.403 * 0.286 0.406 1.000 A16 0.127 0.132 0.320 * 0.208 0.147 -0.091 -0.044 0.397 * 0.390 * 0.175 0.122 0.165 0.084 0.109 0.088 1.000 A17 0.082 0.031 0.046 0.015 -0.116 0.031 -0.066 0.075 0.260 * 0.092 0.006 -0.007 0.126 -0.046 0.133 -0.031 1.000 In this study, which investigated the prevalence of NSSI and associated factors in Chinese adolescents with mood disorders, a considerable proportion of adolescents (62.9%) reported NSSI, which was linked to adverse psychological outcomes such as hopelessness and suicidal thoughts. Compared with adolescents, their parents appeared to underestimate the adverse psychological influences related to NSSI. Overwhelming academic pressure and limited time for leisure or entertainment were dominant factors that contributed to NSSI, as reported by both the adolescents and their parents. Correlation analysis also indicated positive relationships between hopelessness, suicide and NSSI. The percentage of female adolescents who engaged in NSSI was several times greater than that of male adolescents in our study, consistent with previous findings ( Watanabe et al., 2012 Watanabe et al., 2012 ; Geulayov et al., 2018 Geulayov et al., 2018 ). We also found a strong association between NSSI and suicidal thoughts. Several factors of NSSI were identified according to the responses from both the adolescent and parent groups, including "hopelessness," "lack of understanding of psychological pain," and "limited time for leisure and entertainment due to large amount of schoolwork." In addition, factors such as "poor family relationship," "school bullying," "embarrassment or shame due to family financial burden" were only reported by a minority of participants. Most adolescents engaging in NSSI were aged 13 to 18 years, and this is consistent with many other studies on NSSI ( Tang et al., 2013 Tang et al., 2013 ; Geulayov et al., 2018 Geulayov et al., 2018 ; Hiscock et al., 2018 Hiscock et al., 2018 ). Adolescents in this age group seem to be more likely to engage in NSSI. As mentioned previously, the pattern of NSSI tends to fit the iceberg model ( Tang et al., 2013 Tang et al., 2013 ; Geulayov et al., 2018 Geulayov et al., 2018 ), indicating that a significant proportion of individuals engaging in NSSI are not presenting to hospitals. The actual number of adolescents with mood disorders who engage in NSSI is probably extremely high. Therefore, more attention to NSSI in adolescents is needed. NSSI was associated with adverse psychological outcomes such as hopelessness, which is consistent with another study ( Watanabe et al., 2012 Watanabe et al., 2012 ). One possible explanation for this is that engaging in NSSI may be an approach to reduce the feeling of hopelessness and make oneself feel better ( Franklin et al., 2010 Franklin et al., 2010 ; Weinberg and Klonsky, 2012 Weinberg and Klonsky, 2012 ; Bresin and Gordon, 2013 Bresin and Gordon, 2013 ). In this study, we also found a close relationship between NSSI and suicidal thoughts. Previous studies have suggested that NSSI can be considered a robust predictor of future suicide attempts ( Guan et al., 2012 Guan et al., 2012 ; Borschmann et al., 2017 Borschmann et al., 2017 ; Morgan et al., 2017 Morgan et al., 2017 ; Mars et al., 2019 Mars et al., 2019 ). Therefore, young adolescents with mood disorders reporting NSSI are at high risk of suicide, which warrants special attention. With regard to social and family factors linked to NSSI, the results from previous studies have varied. In several previous studies, higher parental invalidation and dysfunctional peer relationships were observed in adolescents who engaged in NSSI ( Tan et al., 2014 Tan et al., 2014 ; Gandhi et al., 2019 Gandhi et al., 2019 ; Victor et al., 2019 Victor et al., 2019 ). The relationship between siblings may also influence this issue, as shown by Tschan et al. (2019) Tschan et al. (2019) . Lauw et al. (2018) Lauw et al. (2018) found that the marital status of parents and childhood abuse were not associated with NSSI in adolescents. The impact of the quality and structure of family relationships and other social factors on NSSI in adolescents requires further research. Of note, parents of adolescents engaging in NSSI seem not to be aware of their children's self-harm behaviors or suicidal thoughts. This may be due to the emotional isolation of these adolescents, as it was found in this study that many of the adolescents reported a lack of being understood or having nobody to talk with. Another explanation is that Chinese traditional culture makes adolescents feel ashamed of being mentally ill and parents unconsciously choose to ignore emotional and behavioral abnormalities in their children. Inadequate awareness of NSSI among parents may provide the conditions for adolescent NSSI. There are several limitations in this study. First, the correlation between NSSI and other factors found in this study did not indicate any causality. Further analysis is needed to identify predictors of NSSI, which was beyond the scope of this study. Second, the sample size in this study was too small for detailed interpretation, and was limited to adolescents with mood disorders. We also did not record the clinical diagnosis of the participants, although a diagnosis of mood disorder was required for eligibility. Third, of the 70 adolescent participants, 8 were aged over 18 years and the maximum age was 25 years. Inclusion of these participants in the final analysis may also have had an impact on our results. Fourth, the actual prevalence of current or past NSSI in this population was difficult to estimate due to self-report or recall bias. Some adolescents may feel reluctant to report self-injury behaviors, and others may have difficulty in recalling these experiences. In conclusion, NSSI is a common problem among Chinese adolescents with mood disorders. Given the perniciousness of NSSI, parents, schools, and public health authorities should recognize this issue and implement early and effective interventions to help these adolescents. Clinical monitoring for NSSI is also needed, especially in young patients with mood disorders. 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WHO Mental Health Home . https://www.who.int/health-topics/suicide#tab=tab_1 https://www.who.int/health-topics/suicide#tab=tab_1 Suicide prevention. WHO Mental Health Home Shaohua HU contributed to the conception and design of the study and provided administrative support. Yixin WANG, Jianbo LAI, Chanchan HU, Hongbo MENG, and Duo LYU participated in the collection and assembly of data. Yixin WANG and Duo LYU performed data analysis and interpretation. Yixin WANG and Jian-bo LAI were involved in the writing of the manuscript. All authors have given final approval of the manuscript for publication, and therefore have full access to all the data in the study and take responsibility for the integrity and security of the data. This work was supported by the National Key Basic Research Program of China (No. 2016YFC1307100) and the Program of Health and Family Planning Commission in Zhejiang Province (No. 2020KY548), China. 10.1631/jzus.B2000679 1673-1581（2021）03-0233-08 2020-10-26 2020-11-24 2021-03-01 2021-03-15 2022-05-09 © Zhejiang University Press 2021 Yixin WANG, Jianbo LAI, Chanchan HU, Hongbo MENG, Duo LYU, and Shaohua HU declare that they have no conflict of interest. This study was approved by the Hospital Ethics Committee of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China. All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 (5). Informed consent was obtained from participants for being included in the study. Compliance with ethics guidelines 浙江大学学报（英文版）（B辑：生物医学和生物技术） 3 22