By Anne Harding NEW YORK (Reuters Health) - A new treatment that can be given on an outpatient basis resulted in a statistically significant reduction in methamphetamine use by addicted individuals, according to the first clinical study of the protocol. Of the 50 patients who entered the study, 36 men and women completed the study. The subjects reported using meth on 80% of the 90 days prior to treatment, but they used the drug on just 28% of the 84 days following the first day of treatment, representing a 65% reduction in drug use. "I think we've found the first clinically effective treatment for methamphetamine addiction," the study's lead author, Dr. Harold C. Urschel III, told Reuters Health. Urschel, an addiction psychiatrist, works for Research Across America, a Dallas-based company that performs independent clinical research, reported the findings last week at the annual meeting of the College on Problems of Drug Dependence in Scottsdale, Arizona. Previously, he noted, if he had got a 25% to 30% reduction in drug use among meth addicts with treatment, "I'd be just jumping for joy. Urine tests showed that the study participants were telling the truth about their use or abstinence about 85% of the time. PROMETA consists of a series of intravenous and oral treatments given in a doctor's office over the course of 30 days. Developed by the for-profit company Hythiam, Inc., it consists of FDA-approved drugs used "off-label," meaning the FDA has not approved their use for this condition. PROMETA consists of an anti-anxiety drug from the class known as benzodiazepine antagonists, and a drug that modulates one of the brain's main signaling systems, GABA. Also included are nutritional supplements. Among the 31 people who completed a series of questionnaires measuring their drug craving, 30 reported a reduction in craving, while one reported no change. Meth addicts often drop out of treatment in the first few days, Urschel noted, largely because the drug has damaged their brain so concentration is extremely difficult. But in the current study, he said, "the patients' memory and concentration almost uniformly across the board came back," as soon as the first day of treatment. "That alone allows the people to focus on sitting in intensive outpatient treat and learn the skills necessary to staying sober." While the mechanism for the protocol's effectiveness is not clear, Urschel said the main hypothesis is that it somehow restores the function of the GABA system, which has been damaged by drug or alcohol use. In healthy people, he noted, the neurotransmitter helps people to stay calm and relaxed. Treatment may restore its function, reducing anxiety. The current study did not include any psychosocial interventions, which are usually part of the PROMETA protocol. Urschel said that the results would probably be better if the drug compound was given with these interventions.