Light pollution may elevate Alzheimer’s risk

According to new research from Rush, outdoor light at night may be a major risk factor for Alzheimer’s disease.

Although light pollution has been linked to an increased risk of certain conditions and diseases, this is the first time that light pollution has been linked to Alzheimer’s disease.

The study was conducted at the Rush University System for Health and published in Frontiers in neuroscience.

Our research shows that in the US there is a link between the prevalence of Alzheimer’s disease and light exposure at night, especially in people under 65. Nocturnal light pollution -; an adaptable environmental factor -; may influence the risk of Alzheimer’s disease.”

Robin Voigt-Zuwala, PhD, principal investigator, associate professor at Rush

High American light levels

Although legislation in some states aims to reduce light pollution, nighttime light levels remain high in many parts of the country.

Studying light pollution maps, researchers looked at the lower 48 states and processed medical data related to risk factors for Alzheimer’s disease, dividing the groups based on light intensity. Across the five groups, they found that light intensity was correlated with the prevalence of Alzheimer’s disease, even if some known disease factors were not.

Although the cause is unknown, higher nighttime light intensity was associated with a greater prevalence of Alzheimer’s disease than any other risk factor examined in the study for people under age 65. This suggests that younger people may be more sensitive to the effects of light exposure at night.

“Certain genes may influence early Alzheimer’s disease, and these same genes may cause increased vulnerability to the effects of nighttime light exposure,” Voigt-Zuwala explains. “Additionally, younger people are more likely to live in urban areas and have lifestyles that can increase light exposure at night.”

Reducing light exposure

Light exposure affects the body’s natural sleep-wake pattern, which is called a circadian rhythm. Exposure to light at night can disrupt a person’s circadian rhythm, which can promote inflammation and make a person less resilient and more susceptible to disease. Researchers have not examined light in the home at night or how it can affect health.

Voigt-Zuwala said: “The good news is that simple changes can be made with minimal effort to reduce light exposure at night – adding blackout curtains or sleeping with an eye mask.”

The study results are limited to a subset of the population and further testing is needed to better understand the link between outdoor evening light and Alzheimer’s disease.