September 11, 2024
Turn down those Friday night lights – at least at bedtime.
A new study found that living in areas with a high concentration of streetlights, roadway lighting, illuminated signs and other sources of light pollution may increase the risk of Alzheimer’s disease, especially in younger people.
“We show that in the U.S., there is a positive association between Alzheimer’s disease prevalence and exposure to light at night, particularly in those under the age of 65,” said Robin Voigt-Zuwala, an associate professor at Rush University Medical Center in Chicago and the study’s first author. “Nightly light pollution — a modifiable environmental factor — may be an important risk factor for Alzheimer’s disease.”
For the study, Dr. Voigt-Zuwala and her colleagues analyzed light pollution maps of the lower 48 states. They ranked locales according to intensity of nighttime light, dividing them into five groups from lowest to highest levels of nighttime light pollution, using radiance data collected from NASA satellites. They then correlated the light data with geographical data on Alzheimer’s prevalence from Medicare and the Centers for Disease Control and Prevention.
They found that overall, the higher the levels of light pollution, the greater the prevalence of Alzheimer’s disease. The risk of Alzheimer’s was particularly increased in those younger than 65. But high levels of light pollution seemed to affect older Americans as well, with a greater impact on Alzheimer’s risk than better known risk factors like alcohol abuse, chronic kidney disease, depression and obesity.
States with the most light pollution, including Florida and New Jersey, had the highest rates of Alzheimer’s disease prevalence. States with the lowest light pollution, including Montana, New Mexico, Oregon and Vermont, on the other hand, had the lowest rates of Alzheimer’s prevalence. Examining data from specific counties, which have more uniform light intensities than entire states, showed similar results. The findings were published in the journal Frontiers in Neuroscience.
Exposure to high levels of artificial outdoor light has been linked to other health problems, including obesity, heart disease and some forms of cancer. But this is one of the first studies to examine the connections between light pollution and Alzheimer’s disease.
Bright lights can disrupt sleep and the body’s natural circadian rhythms. A growing number of studies show that poor sleep is linked to an increased risk of cognitive problems and Alzheimer’s disease. Experts theorize that sound sleep may serve a cleansing function, helping to rid the brain of toxins that can contribute to Alzheimer’s.
The study showed only an association between outdoor light pollution and Alzheimer’s prevalence and cannot prove cause and effect. Assessments of light pollution levels were made on a county-wide level and did not consider an individual’s exposure to light in particular towns and neighborhoods. Nor did the authors factor in other risk factors for Alzheimer’s disease. Exposure to air pollutants in urban areas and near roadways, for example, have likewise been linked to an increased risk of Alzheimer’s disease.
The authors note that further study is needed but that awareness about the potential link between nighttime light exposure and brain health may help to curb any long-term ill effects. “Awareness of the association should empower people — particularly those with risk factors for Alzheimer’s disease — to make easy lifestyle changes,” Dr Voigt-Zuwala said. “Easy to implement changes include using blackout curtains or sleeping with eye masks. This is useful especially for those living in areas with high light pollution.”
While the researchers did not examine the effects of inside light in their current study, they note that light exposure inside the home could also have a harmful effect on cognitive health. Blue light emitted from smartphones, computer tablets and other digital devices may be particularly disruptive to a sound night’s sleep, experts say. Using blue-light-filtering reading glasses and avoiding screens near bedtime could help to minimize the detrimental effects of indoor light exposure.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D. Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Robin M. Voigt, Bichun Ouyang, Ali Keshavarzian: Outdoor nighttime light exposure (light pollution) is associated with Alzheimer’s disease. Frontiers in Neuroscience, September 5, 2024
