A supplement of the amino acid N-acetylcysteine may ease the symptoms of compulsive hair pulling, according to a study conducted by researchers from the Minnesota School of Medicine and published in the Archives of General Psychiatry.

Hair-pulling, also known as trichotillomania, is a compulsive disorder that may affect as many as one in seven people at some point. Patients feel a compulsive urge to pull out the hair from their scalps, eyebrows or even eyelashes, sometimes creating bald spots. Some people who suffer from trichotillomania will play with or eat their hair after pulling it out.

Although similar to obsessive-compulsive disorder, trichotillomania is not the same condition and does not respond well to antidepressants or other drugs. The condition is not well understood, but the neurotransmitters dopamine and serotonin are believed to play a role.

Researchers gave a number of trichotillomania patients a 1,200 mg supplement of N-acetylcysteine every day for six weeks. This dose was continued for another six weeks in patients who appeared to be responding, and doubled in patients who did not appear to be responding.

Fifty-six percent of patients treated with N-acetylcysteine demonstrated "much or very much improved" symptoms, compared with only 16 percent of those treated with a placebo. There were no adverse side effects reported.

The amino acid treatment proved more effective than the success rate of drug treatments, and was on par with the effectiveness of behavioral therapy or a drug-therapy combination.

Researchers said that even if the amino acid treatment proves successful in further studies, behavioral therapy should still be used to try and treat the underlying psychological causes of hair pulling.

Previous studies haves suggested that N-acetylcysteine supplements may also be effective at treating symptoms of bipolar disorder, obsessive-compulsive disorder and schizophrenia. They are also used to treat acetaminophen (Tylenol) overdoses and nasal mucus buildup.

The supplements are available over the counter and by prescription.