Researchers whose findings were published in the Canadian Medical Association Journal also noted a change in the preferred methods of suicide, from guns or poisons to suffocation by strangulation.

"Our message is that all suicide is a tragedy and the trend is very disturbing," said lead author Robin Skinner, an epidemiologist with the Public Health Agency of Canada in Ottawa.

In 1980, 0.6 per 100,000 girls between the ages of 10 to 14 committed suicide, rising to 0.9 per 100,000 in 2008. But among girls 15 to 19 years old, the rate rose from 3.7 per 100,000 in 1980 to 6.2 per 100,000 in 2008.

Overall, suicide is the second leading cause of death for Canadians between 10 and 19 years old, after accidents.

Skinner told Reuters Health there was a small improvement in suicide rates for all Canadians in that age group between 1980 and 2008.

Whereas 6.2 of every 100,000 young Canadians killed themselves in 1980, the rate fell to 5.2 per 100,000 in 2008 -- in general, a 1 percent annual decline over nearly three decades.

The group found there was no significant change in the suicide rate for boys 10 to 14 years old. In 2008, 1.6 per 100,000 committed suicide. But the rate for those aged 15 to 19 fell considerably, from 19 per 100,000 in 1980 to 6.2 per 100,000 in 2008.

The study did not examine why the rates for girls increased over the 28-year period, or why that of boys dropped, but they did point out a steady rise among both sexes in deaths by suffocation.

Previous research has found that young people perceive hanging to be a "clean, quick and painless method" of suicide, according to the authors.

In addition, they write, a so-called "hocking game" has grown in popularity among kids and teens during the study period. It involves either strangling the throat or applying pressure to the chest to achieve euphoria from oxygen deprivation.

"The 'game' can turn deadly if the participant being choked is physiologically susceptible or if the pressure is not released quickly enough after the loss of consciousness," Skinner's team wrote.

"Deaths resulting from the 'choking game' have the potential to be misclassified as suicides, especially when the 'game' is played alone."

A commentary by Laurence Kirmayer, of the Department of Psychiatry at McGill University in Montreal, that accompanied the study suggested the increase in suicides among girls might be explained by the more lethal methods being used to attempt suicide in general.

"Girls tended to use poisoning not gunshots, hanging is potentially more lethal than poisoning, partly because people often use sublethal doses of pills or other substances," he told Reuters Health in an email. SOURCE: bit.ly/HdqVhu and bit.ly/Hj1ugM

(Reporting from New York by Andrew Seaman at Reuters Health; Editing by Elaine Lies and Paul Tait)

• A Permanent Economic Emergency