When it comes to Alzheimer’s disease, no one yet knows the best way to halt the gradual slips in memory and other brain functions that are the hallmarks of the disease. But researchers in the Netherlands have found that a simple nonmedical intervention may be just as effective as drugs to keep elderly patients sharp.
Eus Van Someren at the Netherlands Institute for Neuroscience reports in the Journal of the American Medical Association that elderly patients with dementia who were exposed to bright lights in long-term care facilities scored 5% better on cognitive tests and had 19% fewer depressive symptoms than similar patients residing in less well-lit facilities. In the study, Van Someren’s group used 1,000-lux bulbs in overhead lights, which is equivalent to the brightness of television studio lights, and compared their effects to those of 300-lux bulbs, which are found in office and retail settings. “I was surprised by the results on cognition,” says Van Someren. “I had expected, based on previous studies, that we would find improvements in sleep. But I hadn’t expected to see the effect on cognition.”
The patients exposed to bright lights consistently scored one point higher on cognition tests during the five-year study than those residing under normal light conditions. “The results are interesting, and worth paying attention to,” says Dr. Marilyn Albert, a neurologist at Johns Hopkins School of Medicine. Light, the study’s authors suspect, works on the body’s circadian clock, which is regulated by a cluster of cells in the brain’s hypothalamus. Those cells release agents that, along with the hormone melatonin, help to regulate the body’s sleep-wake cycle and are responsible for alerting the brain when the cycle is broken — as in the case of jet lag, for example. “With disregulation of the circadian rhythm, there are lots of changes in hormonal status and metabolites in the blood,” says Albert. “So you can imagine that would affect cognition.”
With age, the cells in the hypothalamus become less active. It’s a situation that is made worse by the fact that the elderly tend to spend less time outdoors in the sunlight, which increases melatonin production in the pineal gland, causing sleep and mood disturbances. In earlier studies, Van Someren showed that Alzheimer’s patients living in homes who preferred darker rooms were the most restless during the night. Combined with this study’s findings, he now believes that the inactivity of these biological-clock cells can be reversed.
Van Someren also notes that the gain in cognitive test scores is the same benefit that Alzheimer’s patients can expect from taking cholinesterase inhibitors, which stall the advent of dementia by strengthening communication between brain nerve cells. “Because it gives the same effect, on average, it may make sense for people to consider living in a better-lit environment,” he says. While experts don’t feel the results are enough to constitute a treatment for symptoms, when it comes to staving off the mental decline of dementia, a new rule of thumb might be “Let there be light.”
