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Keywords:

  • adolescents;
  • self-injury;
  • suicidal ideation

Abstract

  1. Top of page
  2. Abstract
  3. SUBJECTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

We examined differences in the prevalence of a lifetime history of self-cutting and suicidal ideation by age among junior and senior high-school students. Histories of self-cutting and suicidal ideation were reported by 9.9% and 40.4% of the students. Among early teens, females were more likely to report suicidal ideation than males, and among late teens, females were more likely than males to report self-cutting.

DELIBERATE SELF-HARM, INCLUDING self-cutting, is a common mental health problem among adolescents.1 Although it is well known to be closely associated with future suicide,1,2 few epidemiological studies on self-harm have been reported in Japan.3–5 For prevention of suicidal behavior in adolescents, epidemiological studies on the onset of self-cutting should be performed.

The present study aimed to examine differences in the prevalence of self-cutting and suicidal ideation by age, and to determine the age at which Japanese adolescents start to engage in self-cutting.

SUBJECTS AND METHODS

  1. Top of page
  2. Abstract
  3. SUBJECTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

The subjects were 1726 junior and senior high-school students (794 males and 932 females; aged from 12 to 17 years; mean age ± SD: 14.5 ± 1.4 years) who consented to participate in this study of 1784 students (96.7%) at six coeducational schools. The students were drawn from three public junior high schools, two public senior high schools, and one private senior high school. All schools are located in urban and suburban areas of Kanagawa and Saitama prefectures in Japan. The academic levels of the three senior high schools ranged widely. We classified the three high schools into three types, one in each type, by the percentage of graduates from each school going to universities in the previous year: elite (over 90%), average (50–90%), and below average (less than 50%).

Each of these schools invited the first author of this paper to give a lecture as a drug abuse prevention class, held from April 2006 to March 2007. Such classes have recently been given in many high schools nationwide under guidance from the Japanese government. This study was approved by the principal and the Parents and Teachers Association of each school. Written informed consent was obtained from all participants.

We administered a self-reporting questionnaire originally designed to evaluate lifetime histories related to self-cutting and suicidal ideation. Question 1 (lifetime history of self-cutting) was: ‘Have you ever cut yourself deliberately with a knife or other sharp object?’. Question 2 (lifetime history of suicidal ideation) was: ‘Have you ever felt that you wanted to die, or wanted to kill yourself?’. These questions were answered with ‘Yes’ or ‘No.’ This questionnaire also included questions on substance abuse such as tobacco, alcohol, and illicit drugs, although these variables were not analyzed in the present study.

These self-reporting questionnaires were administered after the lecture on drug abuse prevention. Completed and unsigned questionnaires were immediately collected by the first author. All statistical analyses were performed with SPSS software for Windows (version 12.0, SPSS, Chicago, IL, USA). We employed the χ2 test to compare the prevalence of lifetime histories of self-cutting and suicidal ideation between genders by age and between ages by gender. The level of significance was set at P < 0.05 and all P-values were two-tailed.

RESULTS

  1. Top of page
  2. Abstract
  3. SUBJECTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Table 1 shows that 165 students (9.9%) reported a lifetime history of self-cutting and 687 students (40.4%) reported a lifetime history of suicidal ideation.

Table 1.  Prevalence of lifetime history of self-cutting and suicidal ideation Thumbnail image of

Regarding gender difference, lifetime histories of self-cutting and suicidal ideation were significantly more frequent in the females than in the males. A lifetime history of self-cutting was significantly more frequent in females than in males in 16- and 17-year-old students, while it showed no significant gender difference in ages below 16. A lifetime history of suicidal ideation was more frequent in females than in males in 13-, 14-, and 15-year-old students, while it showed no significant gender difference in the other ages (Table 1).

Regarding age difference, a lifetime history of self-cutting was more frequent in the 13-year-olds than in the 12-year-olds as a whole and in the males, while it was not significantly different among the other age groups. A lifetime history of suicidal ideation showed no significant age differences (Table 1).

In addition, lifetime histories of self-cutting and suicidal ideation were compared among the three senior high schools (each of different academic levels). The students in the average high school reported significantly higher lifetime histories of self-cutting (17.4%, P < 0.001) and suicidal ideation (50.0%, P = 0.001) than students in the elite high school (self-cutting, 4.5%; suicidal ideation, 31.1%) and the below-average high school (self-cutting, 5.7%; suicidal ideation, 44.3%).

DISCUSSION

  1. Top of page
  2. Abstract
  3. SUBJECTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

In the present study, differences were found in histories of self-cutting between 12- and 13-year-old students, particularly among males. Previous studies in other countries found that adolescents were likely to first perform self-harm at 12–14 years.1,6 In our previous study, the average age when self-injuring adults reported to have first engaged in self-cutting was 13 years.3 These findings suggest that many self-cutting students, particularly males, are likely to start self-cutting at approximately 13 years. Thus, education to prevent deliberate self-harm should be provided before students enter junior high school. However, attention needs to be paid to the fact that there were no differences in histories of suicidal ideation between 12 years olds and those older than 13.

The present study also found that among the late teen students, females are more likely than males to report self-cutting, despite no difference in the prevalence of suicidal ideation. This contrasts with the finding that there are no gender differences in self-cutting among early teen students. This appears to suggest that the recent epidemic of self-cutting in Japan,4 possibly influenced by media, may affect males as well as females in the early teens, while it may not affect late teen males. However, this speculation cannot satisfactorily explain another finding in the present study, namely, that early teen females are more likely to report suicidal ideation than males despite there being no difference in the prevalence of self-cutting.

What can explain this inconsistency? Hawton et al. reported that males are more likely than females to commit suicide, while females are more likely to have suicidal ideation, suggesting that females may be superior to males in the ability to express distress, thus helping them to avoid committing suicide.1 This leads us to suspect that males may tend to deny suicidal ideation, while both suicidal ideation described by early teen females and self-cutting performed by late teen females may not necessarily mean an urgent death wish but instead reflects a method of communicating distress to others.

This study had three main limitations. First, the sample representation may be biased because all six participating schools also happened to invite the first author as a lecturer for the class on prevention of drug abuse. Second, the influence of the lecture and other questions included in our self-reporting questionnaire cannot be disregarded since this investigation was performed after the lecture. However, topics of self-cutting and suicide were not addressed in the lecture. Finally, the difference in the type of schools does not seem to have influenced the findings. The present study cannot exclude the possibilities that contagion phenomenon of self-cutting and suicidal ideation might break out in the average-level senior high school because this school showed the highest prevalence.

Despite these limitations, this is the first report detailing differences in a lifetime history of self-cutting and suicidal ideation by age among Japanese adolescents.

REFERENCES

  1. Top of page
  2. Abstract
  3. SUBJECTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES
  • 1
    Hawton K, Rodham K, Evans E. How do adolescents who deliberately self-harm or have thought of self-harm differ from other adolescents? In: HawtonK, RodhamK, EvansE (eds). By Their Own Young Hand: Deliberate Self-Harm and Suicidal Ideas in Adolescents. Jessica Kingsley Publisher, London, 2006; 6593.
  • 2
    Owens D, Horrocks J, House A. Fatal and non-fatal repetition of self-harm. Systematic review. Br. J. Psychiatry 2002; 181: 193199.
  • 3
    Yamaguchi A, Matsumoto T, Odawara T et al. Prevalence of self-mutilation in Japanese University students; a study using self-reporting questionnaire. Clin. Psychiatry (Seishinn Igaku) 2004; 46: 473479 (in Japanese).
  • 4
    Yamaguchi A, Matsumoto T. Self-mutilation among female high-school students. An association with smoking and drinking, piercing, and bulimic tendency. Clin. Psychiatry (Seishinn Igaku) 2005; 47: 515522 (in Japanese).
  • 5
    Izutsu T, Shimotsu S, Matsumoto T et al. Deliberate self-harm and childhood histories of Attention-Deficit/Hyperactivity Disorder (ADHD) in junior high-school students. Eur. Child Adolesc. Psychiatry 2006; 14: 15.
  • 6
    Favazza AR, Derosear DO, Conterio K. Self-mutilation and eating disorders. Suicide Life Threat. Behav. 1989; 19: 353361.