US suicide rates appear to be on the rise, driven mostly by aged²" target="_blank">middle-aged¹ white women, researchers reported on Tuesday.

They found a disturbing increase in suicides between 1999 and 2005 and said the pattern had changed in an unmistakable way.

The overall suicide rate rose 0.7 percent during this time, but the rate for white men aged 40 to 64 rose 2.7 percent and for middle-aged women 3.9 percent, the team at Johns Hopkins University in Baltimore found.

"The biggest increase that we have seen between 1999 and 2005 was the increase in poisoning suicide in women -- that went up by 57 percent," said Susan Baker³, a professor in injury prevention with a special expertise⁴ in suicide.

Writing in the American Journal of Preventive Medicine, Baker, Guoqing Hu and colleagues said they analyzed⁵ publicly available death certificate data from the US Centers for Disease Control and Prevention.

"The results underscore a change in the epidemiology of suicide, with middle-aged whites emerging as a new high-risk group," Baker said in a statement.

Suicide is the 11th leading cause of death in the United States and Baker said the changes are substantial.

"Definitely these are not just little blips," she said in a telephone interview. "We are looking at a big population change."

The middle-aged women and men used various methods to kill themselves -- poisons, prescription⁶ drugs, hanging or suffocation⁷, and firearms, Baker said.

While firearms remain the most common method, the rate of gun suicides decreased while suicide by hanging or suffocation increased by 6.3 percent among men, and 2.3 percent among women.

And international research published in January found that the young, single, female, poorly educated and mentally ill are all at higher risk of suicide.

According to the World Health Organization, suicide rates have increased by 60 percent in the last 45 years. Depression is the leading cause of suicide.

研究人员于本周二发布的一项研究报告称，目前美国的总体自杀率呈上升趋势，其中中年白人女性的自杀率增长尤为显著。

研究人员发现，从1999年至2005年，美国的自杀率总体上升，不过增长“模式”发生了明显变化。

巴尔的摩约翰•霍普金斯大学的研究小组发现，美国的总体自杀率在这一期间增长了0.7%，其中，40岁至64岁白人男性的自杀率上升了2.7%，而中年白人女性的自杀率则上升了3.9%。

从事伤害及自杀预防研究的苏珊•贝克教授说：“这一阶段女性的服毒自杀率增长最为显著，达到57%。”

贝克教授、胡国庆教授及其同事们在研究报告中指出，研究结果主要基于对美国疾病防控中心的死亡证明资料的分析。该研究报告在《美国预防医学期刊》上发表。

贝克在一份声明中称：“研究结果突出了自杀流行病学的一个变化，中年白人女性正在成为一个新的自杀高危群体。”

自杀是美国的第十一大死因。贝克称，这些变化是实质性的。

她在电话采访中说：“显然，这些并不是暂时的小波动，而是整个人口的大变化。”

她说，中年人群的自杀方式有很多种，包括服毒、服药、上吊或窒息以及枪支。

枪支仍是最常用的自杀手段。不过近年来使用枪支自杀的比率有所下降，而上吊或窒息自杀率则有所上升，在男性和女性中的增幅分别为6.3%和2.3%。

今年一月公布的一项国际研究显示，年轻人、单身人群、女性、受教育水平较低者以及精神病患者是几个主要的自杀高危人群。

据世界卫生组织统计，全球自杀率在过去的45年中上升了60%。而抑郁症是自杀的首要诱因。