Although antioxidant treatments do not appear to cause any problems for ALS patients, they do not prevent muscle deteroriation or improve the quality of life for these patients, according to Dr. Richard Orrell of University College London and colleagues.
"Despite substantial literature on the scientific basis for the use of antioxidants in patients with ALS, and the widespread use of these medications by patients, often on the advice of their physician, there is no significant evidence to support their benefit in patients with ALS," Orrell says.
"The antioxidant medications used are generally well-tolerated, and without serious adverse effects. This probably explains their wide use by patients, with or without the advice of their physician," he adds.
The review appears in the January issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
ALS is a fatal disease that causes deterioration of motor nerve cells in the brain and spinal cord. Although researchers are still unsure about the exact causes of the disease, some have suggested that nerve cells in ALS patients are damaged by the accumulation of "free radicals," highly active oxygen particles that bombard and eventually collapse cells.
Antioxidants like vitamins C and E "are commonly advised by physicians for patients with ALS," on the assumption that the drugs may help mop up excess free radicals.
According to Lucie Bruijn, science director at The ALS Foundation, studies of antioxidant treatments in mice have shown that "they do not, in fact, significantly alter the course of the disease."
The review by Orrell and colleagues included eight studies of antioxidant treatment of 670 patients with varying degrees of ALS. The researchers combined and analyzed data from three of the studies with information on survival rates a year after the treatment had started. The three studies included 426 patients.
In one of the studies, patients took 500 milligrams of vitamin E twice a day. Patients in the second study received a 50-milligram, under-the-skin injection of the antioxidant drug acetylcysteine once a day. In the third study, patients took a combination of two grams of the antioxidant L-methionine, 400 milligram of vitamin E and three 3 x 10-5 selenium doses each day.
After combining all data from the three studies into one analysis, Orrell and colleagues concluded that antioxidant treatments did not significantly boost the survival rates of the studies' patients or improve their symptoms. The outcome was the same when each of the studies was considered separately, the researchers found.
"Generally, the studies were poorly designed," Orrell says, noting the small number of patients and relatively treatment periods for most studies.
Nevertheless, Orrell says physicians may keep prescribing antioxidants to ALS patients because the drugs are inexpensive and relatively safe, even though "there is no substantial clinical trial evidence to support their clinical use."
"This may be an important consideration when other unproven medications may have a higher potential risk of adverse effects and higher cost," Orrell says.
There is no cure for ALS. The drug Rilutek® (riluzole), which is not an antioxidant, is the only treatment approved by the Food and Drug Administration to slow the progress of ALS.
According to the National Institute of Neurological Disorders and Stroke, about 5,000 Americans are diagnosed with ALS each year. Patients with ALS usually die within five years of their diagnosis.
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Interviews: Contact Dr. Richard Orrell at 44-20-7830-2387 or r.orrell@rfc.ucl.ac.uk.
1Orrell et al. Antioxidant treatment for amyotrophic lateral sclerosis /motor neuron disease. The Cochrane Database of Systematic Reviews 2005, Issue 1 The Cochrane Collaboration is an international nonprofit, independent organization that produces and disseminates systematic reviews of health care interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. Visit http://www.cochrane.org for more information.