Another Type of Pollution Is Now Tied to Alzheimer’s Risk

If you live in an area with a lot of light pollution, you are not alone: As much as 80% of the world’s population is exposed to excessive artificial outdoor lighting.

Now, research has found that higher levels of light pollution are associated with a greater prevalence of Alzheimer’s disease, the most common cause of dementia. Grants from the National Institutes of Health funded the research.

This research follows multiple studies over the past few years that have linked air pollution — including from vehicle exhaust and wildfires and farming — to an increased risk of dementia.

For the recent study, researchers analyzed light pollution maps of the lower 48 states and medical data on known or suspected risk factors for being diagnosed with Alzheimer’s disease.

Among people aged 65 and older, nightly light pollution was more closely associated with Alzheimer’s prevalence than several other risk factors for the disease, including:

• Alcohol abuse
• Chronic kidney disease
• Depression
• Obesity

But light pollution appears to pose an especially potent risk for people younger than 65. Light exposure at night was the No. 1 risk factor for Alzheimer’s among people in this age group.

Light pollution can disrupt circadian rhythms, which can create sleep issues. A lack of quality sleep has been associated with a higher risk of neurodegenerative diseases such as Alzheimer’s.

The researchers said it was unclear why light pollution had a more dramatic impact on younger people. However, they speculated that it might be due to differences in light sensitivity in some young people. They also noted that younger people are more likely to live in urban areas and have lifestyles that increase their exposure to light pollution.

Fortunately, there are ways to combat light pollution. The researchers suggest taking steps such as wearing a sleep mask or installing blackout curtains.

They also urged people to be aware of sources of indoor light that could hamper sleep, such as exposure to blue light. They recommend using blue light filters, changing to warm lighting and installing dimmers to reduce light exposure.