Comparative study of the prevalence of suicidal behavior and sexual abuse history in delinquent and non-delinquent adolescents

Authors


Toshihiko Matsumoto, MD, PhD, Center for Suicide Prevention, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8553, Japan. Email: tmatsu@ncnp.go.jp

Abstract

The present study examined the prevalence of suicidal behavior and sexual abuse history in delinquent and non-delinquent adolescents aged 15–17 years. Results showed that delinquent adolescents, particularly girls, more frequently reported histories of suicidal behavior and sexual abuse than non-delinquent adolescents.

SUICIDE IS ONE of the most important health problems in Japan. Although suicide of adolescents accounts for only 2% of all cases of suicide, it is a major cause of death in this generation of adolescents.1 Identification of suicidal adolescents and intervention to prevent suicide is therefore required.

Previous studies have identified many risk factors predicting fatal or non-fatal suicide attempts by adolescents.2–6 Such risk factors do not only include present depression2 and substance abuse,3 and a history of suicidal behavior (injuring oneself, having suicidal ideation, and attempting suicide),4 which are common to adults, but also antisocial behavior5 and sexual abuse history,6 which are specific to adolescents and young adults. These results suggest that delinquent adolescents may be a high-risk group for suicidal behavior because they frequently have a history of sexual abuse.7 To our knowledge, however, no comparative studies have examined suicidal behavior and sexual abuse history in delinquent adolescents.

The purpose of the present study was to clarify the prevalence of suicidal behavior and sexual abuse history in delinquent adolescents compared with non-delinquent adolescents.

METHODS

A pool of 316 adolescents (99.2%) who were continuously incarcerated in the Yokohama Juvenile Classification Home located in Kanagawa prefecture, Japan between October and December 2007 was identified. A total of 301 adolescents from this pool consented to participate in the study and 135 adolescents (113 male, 22 female; mean age ± SD, 16.2 ± 1.0 years; range: 15–17 years) were selected as subjects (delinquents). The subjects were termed ‘delinquent adolescents’ in the present study.

The controls (students) were 316 high-school students (116 male, 200 female; mean age ± SD, 16.2 ± 0.7 years; range: 15–17 years) who consented to participate in this study from a pool of 368 students (85.9%) at two coeducational public schools located in suburban areas of Kanagawa prefecture. These schools invited the first author to give a lecture at a drug abuse prevention class in December 2007. The controls were named ‘non-delinquent adolescents’ in the present study.

We administered a self-reporting questionnaire originally designed to evaluate lifetime histories of suicidal behavior, illicit drug use, and experiences of abuse that included the following questions: Q1 (self-injury), ‘Have you ever injured yourself deliberately e.g., by cutting yourself?’; Q2 (suicidal ideation), ‘Have you ever seriously wanted to kill yourself?’; Q3 (suicide attempt), ‘Have you ever actually taken action on a feeling of seriously wanting to kill yourself?’; Q4 (illicit drug use), ‘Have you ever used any illicit drugs?’; and Q5 (sexual abuse), ‘Have you ever been forced to have sexual intercourse against your will?’ All questions were answered ‘yes’ or ‘no’.

The self-reporting questionnaires were administered within a week of admission to the juvenile classification home, and after the lecture on drug abuse prevention in the schools. We explained to all participants that they could refuse to participate in this study, and that the information obtained from each participant would be kept confidential. The address of the first author was provided so that those suffering from mental health problems could consult with him. Completed and unsigned questionnaires in each institution were immediately collected by the first author. This study was approved by the director of the classification home, and by the principal and the Parents and Teachers Association of each school.

All statistical analyses were performed using SPSS software for Windows (version 15.0, SPSS, Chicago, IL, USA). We used the χ2 test to compare suicide-related behavior, illicit drug use, and experiences of abuse, and used Student's t-test to compare ages. We also sought Pearson's association coefficients to clarify associations of sexual abuse with self-injury, suicidal ideation, suicide attempt, and illicit drug use in each gender. The level of significance was set at P < 0.05 and all P were two-tailed.

RESULTS

Table 1 compares ages, histories of suicidal behavior, illicit drug use, and sexual abuse of the delinquent adolescents and non-delinquent adolescents separately by gender. No significant differences in age were found between groups for either gender.

Table 1.  Subject characteristics
 Maleχ2 or tFemaleχ2 or t
Delinquent adolescentsNon-delinquent AdolescentsDelinquent adolescentsNon-delinquent Adolescents
n = 113n = 116n = 22n = 200
  • *

    P < 0.05;

  • **

    P < 0.01;

  • ***

    P < 0.001.

Age (years) (mean ± SD)16.2 ± 0.816.2 ± 0.70.276 (t)16.4 ± 1.416.4 ± 0.60.276 (t)
Self-injury (%)13.37.32.699 (χ2)36.410.611.576**2)
Suicidal ideation (%)21.218.30.370 (χ2)54.526.47.582**2)
Suicide attempt (%)6.21.25.268*2)27.33.022.837***2)
Illicit drug use (%)3.50.63.185 (χ2)22.70.046.274***2)
Sexual abuse (%)8.60.611.103**2)59.14.365.064***2)

Among boys, histories of suicide attempt and sexual abuse were significantly more frequent in delinquent adolescents than non-delinquent adolescents, while no significant differences in histories of self-injury, suicidal ideation, or illicit drug use between groups were found. Pearson's association coefficient indicated a significant association of sexual abuse only with self-injury (0.178, P < 0.01).

In contrast, among the girls, histories of self-injury, suicidal ideation, suicide attempt, illicit drug use, and sexual abuse were significantly more frequent in delinquent adolescents than non-delinquent adolescents. Pearson's association coefficient indicated a significant association of sexual abuse with self-injury (0.246, P < 0.001), suicide ideation (0.145, P < 0.05), suicide attempt (0.256, P < 0.001), and illicit drug use (0.204, P < 0.01).

DISCUSSION

In the present study delinquent adolescents were more likely to report histories of suicidal behavior than non-delinquent adolescents. This finding confirmed the results of a previous study that identified antisocial behavior or a criminal record as one of the risk factors for fatal and non-fatal suicide attempts in adolescents.5 Delinquent girls, in particular, showed broad self-destructive tendencies including self-injury, suicidal ideation, suicide attempt, and illicit drug use. It is speculated that such tendencies are caused by a sexual abuse history commonly found in delinquent female subjects because the present study demonstrated the significant associations between sexual abuse and broad self-destructive behaviors in girls, which was consistent with a previous study.8 Delinquent girls are considered to be a high-risk group for suicidal behavior.

The present study also produced valuable results about the prevalence of a history of sexual abuse in delinquent boys and non-delinquent adolescents. Although the present findings confirmed a previous study reporting that male subjects incarcerated in correctional institutions are more likely to have a history of sexual abuse than the general population,9 sexual abuse history in male subjects appears to involve an important clinical implication for forensic practice as well as for suicide prevention. While Hawton et al. showed that male victims of sexual abuse were more likely to display serious suicidal tendencies than female victims,4 Lisak et al. indicated that male subjects who were sexual abuse victims in childhood are likely to commit sexual offenses in the future.10 Further studies on this topic are required.

The present study had three main limitations. First, the sample may have been biased. Second, the influence of the lecture by the first author on the students cannot be excluded. Last, data were acquired via self-reporting questionnaires rather than by a semistructured interview or a collection of collateral information. Despite these limitations this is the first report indicating the differences in prevalence of suicidal behavior and history of sexual abuse between delinquent and non-delinquent adolescents.

Ancillary