LONDON – One in 12 adolescents intentionally harms themselves, but the behavior persists into young adulthood in only 10% cases, according to the findings of a large, population-based, longitudinal study.
Of 1,802 adolescents aged 14-19 years, 149 (8.3%) admitted to self-harm, with more girls (10%) than boys (6.3%) reporting such behavior (hazard ratio, 1.6).
The behavior resolved without intervention in 90% of cases, however, with just 10% of teenagers who admitted to self-harm during adolescence continuing the behavior into their early adulthood.
"We think the findings offer some reassurance to those working with young people, to family members, parents and teachers," said study author Dr. Paul Moran at a press conference on Nov. 16.
Nevertheless, Dr. Moran, of the Institute of Psychiatry at King’s College, London, added: "We also think it’s important that those living and working with young people are able to spot the signs of persistent distress and that they enable young people to get the help that they deserve for those problems."
The study, published online Nov. 17 (Lancet Nov. 17 [Epub doi:10.1016/S0140-6736(11)61141-0]), provides valuable insight into what happens to teenagers who self-harm when they reach adulthood said Dr. Niall Boyce, a psychiatrist turned senior editor at the Lancet.
"Self-harm, especially self-harm in adolescents ... can be very frightening for everybody involved," Dr. Boyce said. "As with many situations it’s a lack of knowledge that is the root of this fear."
Dr. Boyce noted that the study "gives us an idea of how this problem develops, which is extremely useful for clinicians because it means that we can give some idea of prognosis."
The study involved 1,943 adolescents recruited from 44 government, Catholic, and independent schools in the state of Victoria, Australia, between 1992 and 2008 as a representative, random sample of the teenage population. Participants were assessed at nine time points via self-administered online questionnaires and by telephone interviews. At study entry, the mean age of participants was 15 years, and at study end it was 29 years.
Self-harm was broadly categorized into five types: cutting or burning, self-poisoning, deliberate nonrecreational risk-taking, self-battery, and other self-harming behaviors such as self-drowning, hanging, intentional electrocution, and suffocation.
"Underpinning all this was a definition that this was an act with a nonfatal outcome which was initiated deliberately by individuals with the intention of causing harm to themselves," Dr. Moran said.
Although a substantial proportion of self-harm was noted in adolescents, the frequency of self-harm reduced in early adulthood. Indeed, of 1,652 participants who were observed as both adolescents and as young adults, 136 reported self-harm, with only 14 (10%) reporting continued self-harm into adulthood. All but one of these was female.
Cutting and burning were the most common types of self-harm reported by 4.6% of adolescents and by 1.2% of young adults. Self-poisoning or taking an overdose was reported by 1.9% and 0.7%, respectively, with self-battery (1.7% vs. 0.6%), nonrecreational risk taking (1.7% vs. 0.6%), also reported by a higher number of adolescents than young adults.
Dr. Moran noted that self-harm is a clearly a sign of significant emotional difficulties, with depression and anxiety increasing the risk of self-harm almost fourfold (hazard ratio, 3.7). High-risk alcohol use (HR, 2.1) and cannabis misuse (HR, 2.4) doubled the risk of self-harming behavior, with antisocial behavior (HR, 1.9) and smoking cigarettes (HR, 1.8) also influencing the risk of self-harm.
"There was a small group of individuals who started to self-harm as young adults," Dr. Moran said, adding that these individuals "were more likely to report being depressed or anxious in the teenage years."
The research is part of an ongoing project led by Dr. George C. Patton of the Centre for Adolescent Health at the Murdoch Children’s Research Institute in Melbourne. He said that the findings highlight a "window of vulnerability" that occurs around puberty and into the mid-teens.
As to why teenagers might be more vulnerable to self-harming behaviors than adults is unclear, but this could be attributable to structural changes in the brain as much as social and environmental influences.
Self-harm is important, as hospital-based studies have shown that it significantly increases the risk of completed suicide, noted Dr. Keith Hawton, a consultant psychiatrist and the director of the Centre for Suicide Research at Oxford University.
Dr. Hawton, who was not involved in the study, said the findings of this community-based study are applicable worldwide. "We’ve done a comparative study involving a number of countries and the pattern of self-harm seems to be very similar." While there is some international variation, "it is all in the same ballpark."