Just six months of yoga significantly reduces fatigue in people with multiple sclerosis (MS), but it has no effect on alertness and cognitive function, says a new Oregon Health & Science University (OHSU) study.

The study, published in the journal Neurology, found that yoga is as good as a traditional aerobic exercise programme in improving measures of fatigue, a common and potentially disabling symptom of MS. It was the first randomized, controlled trial of yoga in people with MS.

The study examined 69 MS patients in three groups: one taking weekly Iyengar yoga classes along with home practice; another taking a weekly exercise class using a stationary bicycle along with home exercise; and a third group placed on a waiting list to serve as a control. Participants were monitored for attention, alertness, mood, anxiety, fatigue and overall quality of life.

The MS study was not designed to determine the impact of yoga on the disease itself, said the study's lead author, Barry Oken, professor of neurology and behavioral neuroscience in the OHSU School of Medicine. Rather, it was intended to determine the effect of yoga and aerobic exercise on cognitive function, fatigue, mood and quality of life among people with MS.

"There are some claims out there that yoga helps MS itself, that it can decrease the number of lesions" in the brain caused by MS, said Oken, director of the Oregon Centre for Complementary and Alternative Medicine in Neurological Disorders (ORCCAMIND) at OHSU. "I am not sure that that's not the case, because stress may have an impact on MS. But that was not what we were trying to show," he added.

Study co-author Dennis Bourdette, professor of neurology in the OHSU School of Medicine and director of the Multiple Sclerosis Center of Oregon, said yoga was studied because many people with MS already are using it and reporting benefits.

An earlier survey of nearly 2,000 MS patients in Oregon and southwest Washington found about 30 per cent of respondents tried yoga. Of those, 57 per cent reported it to be 'very beneficial,' Bourdette noted. Indeed, many chapters of the National MS Society sponsor yoga programmes.

A parallel study by the same OHSU authors, presented in April at the 56th annual meeting of the American Academy of Neurology, found that cognitive function does not improve among healthy seniors in a six-month yoga programme or exercise class, but physical health and quality of life appear to be enhanced.

"The study clearly demonstrates that yoga postures can be modified for use among people with MS who have disabilities caused by their condition and that yoga can be done safely and effectively," he added.

The yoga classes were offered once a week for 90 minutes. Participants were taught up to 19 poses, each held for 10 seconds to 30 seconds with rest periods of 30 seconds to a minute. They also performed breathing exercises to promote concentration and relaxation, as well as progressive relaxation, visualization and meditation techniques. And daily home practice was strongly encouraged.

Of the active or hatha yoga techniques, Iyengar yoga is the most common type practiced in the United States. Participants assume a series of stationary positions that employ isometric contraction and relaxation of different muscle groups to create specific body alignments. There also is a relaxation component.