A common health-food supplement might help ease the urges of people with a compulsive hair-pulling disorder called trichotillomania, U.S. researchers report.

They tested the effectiveness of the amino acid N-acetylcysteine in a 12-week study that included 50 people with an average age of 34. Most had started compulsive hair pulling by age 12.

Some participants were given 1,200 milligrams of N-acetylcysteine every day for the first six weeks and 2,400 milligrams a day for the next six weeks. Others were given a placebo.

After nine weeks, hair pulling was significantly reduced among those taking the supplement. After 12 weeks, 56 percent of the participants taking the supplement reported feeling much or very much improved, compared with 16 percent of those taking the placebo.

The results appear in the July issue of Archives of General Psychiatry.

"Trichotillomania is compulsive in the sense that people can't control it," principal investigator Dr. Jon Grant, an associate professor of psychiatry at the University of Minnesota, said in a news release from the journal. "People feel unable to stop the behavior, even though they know it is causing negative consequences. Some people don't even know they are doing it."

"There are people who have tried all kinds of things that have never worked," Grant said. "The reality is that if you pull your hair and it is on a noticeable part of the body, people are really disabled by this. It's not easy to go out in public if people are noticing your bald spots. Self-esteem is a huge problem. This supplement may offer hope."

N-acetylcysteine lowers brain levels of glutamate, a chemical that triggers excitement.

美国研究人员报告说，一种普通的保健食品增补剂可能有助于减轻患有强迫性拔毛发症状即拔毛发癖的人们拔毛发的冲动。

他们对平均年龄为34岁的50名拔毛发癖者进行了为期12周的研究，测试了一种氨基酸即N-乙酰半胱氨酸的有效性，其中大多数患者在12岁起就有了强制性拔头发的症状。

在头6周，每天给一些参与者服用1200毫克N -乙酰半胱氨酸，在后六周每天给它们服用2400毫克N -乙酰半胱氨酸。给其他人服用的是安慰剂。

经过9个星期，那些服用该增补剂的人拔毛发的次数明显减少。经过12周后， 与16%的服用安慰剂的人相比，经过12周后，相比16%的服用安慰剂的人，56%服用增补剂的参与者感觉强迫性拔毛发的症状明显或非常明显改善。

该研究结果刊登在《普通精神医学纪要》7月刊中。

"拔毛发癖是强迫性的，人们无法自控，"首席调查员乔恩格兰特博士，明尼苏达大学精神病学副教授，在该杂志的一个新闻发布会上说。"人们感觉无法停止该行为，尽管他们知道这种行为会造成消极后果。而有些人甚至不知道自己在拔毛发。"

"人们已经尝试了各种办法来治疗拔毛发癖，可从来没有取得任何效果，"格兰特说。"现实情况是，毛发是身体上的很显眼的部分，可患有拔毛发癖的人真的无力控制这种行为要拔掉自己的毛发。如果人们发现你秃顶的地方，到外面参加社交活动就感觉很不自在，而且自尊受到伤害。而这一增补剂可能给人们带来了希望。"

N -乙酰半胱氨酸能降低大脑中谷氨酸盐的水平，而谷氨酸盐是一种能引起兴奋的化学物质。