June 10 (Bloomberg) -- Exposing dementia patients to about nine hours of daily bright light improved their brain function as well as some Alzheimer's medicines, a study of Dutch nursing-home patients found.

Treatment slowed the pace at which patients lost their ability to carry out ordinary tasks including bathing, dressing and eating by more than 50 percent, compared with those exposed to dim light, according to the study appearing tomorrow in the Journal of the American Medical Association. Memory difficulties were reduced 5 percent.

The study is the first controlled trial of how light affects mental functioning in dementia patients, the researchers wrote. Effects were similar to those of drugs such as Pfizer Inc.'s Aricept and Novartis AG's Exelon, they said.

``On the whole, light treatment could have clinically beneficial effects,'' the authors said in the paper. ``The long- term application of whole-day bright light did not have adverse effects, on the contrary, and could be considered for use in care facilities for elderly individuals with dementia.''

The ceiling-mounted lights, more than three times brighter than those the study used for comparison, also reduced depression 19 percent. Moreover, the researchers found that melatonin, a hormone, improved sleep and that the lights reduced melatonin's side effects.

The study was conducted at 12 group-care facilities in the Netherlands with 189 patients. Ninety percent of the patients, whose average age was 86, were women. About two-thirds probably had Alzheimer's disease, the authors wrote. The disease can't be diagnosed with certainty until after death.

Alzheimer's and small strokes are the two main causes of dementia, according to the U.S. National Institutes of Health.

Lighting

The authors, led by Rixt F. Riemersma-van der Lek of the Royal Netherlands Academy of Arts and Sciences in Amsterdam, didn't assess the costs of installing and powering the lights. Philips Lighting Holding BV, a division of Netherlands-based Royal Philips Electronics NV, supplied lighting. Cambridge Neurotechnology Ltd., a U.K. company, provided equipment for the study at reduced cost. No installation fees were charged.

The patients were exposed to the lights with intensity measuring 1,000 lux from about 9 a.m. to 6 p.m. over an average of 15 months, the authors wrote. Patients in the comparison group were exposed to 300-lux lighting and given a placebo instead of melatonin. Most indoor lighting ranges from 100 to 800 lux, according to the University of Montana's Web site.

Melatonin reduced the time it took patients to fall asleep an average of 19 percent compared with those who took the placebo. Melatonin without bright lights was associated with withdrawn behavior and aggravation. In combination with the light therapy, it reduced aggressive behavior 9 percent, compared with the placebo group.

To contact the reporter on this story: Elizabeth Lopatto in New York at elopatto@bloomberg.net.

Last Updated: June 10, 2008 17:50 EDT