Light pollution increases the risk of Alzheimer's disease

Alzheimer’s disease, a leading cause of cognitive decline, may have an unexpected link to a widespread environmental issue – light pollution.

As artificial illumination continues to fill our cities and suburbs, researchers are now exploring how constant exposure to nighttime light may influence public health.

While streetlights and neon signs enhance safety and urban beauty, this constant glow could have hidden consequences, potentially contributing to an increased risk of Alzheimer’s.

Light pollution and Alzheimer’s disease

In the US, several states have implemented measures to mitigate light pollution. Yet, some parts of the country continue to bathe in high levels of artificial night light.

Suspecting a possible connection between this incessant light exposure and public health, researchers embarked on a study to investigate the association between outdoor light pollution and Alzheimer’s disease prevalence.

“We show that in the US there is a positive association between AD prevalence and exposure to light at night, particularly in those under the age of 65,” noted study lead author Dr. Robin Voigt-Zuwala, a professor at Rush University Medical Center.

“Nightly light pollution – a modifiable environmental factor – may be an important risk factor for Alzheimer’s disease.”

The higher the intensity, the greater the risk?

The investigative team scrutinized light pollution maps of the continental United States and considered various medical data known to influence Alzheimer’s disease risk.

They produced data reflecting the nighttime light intensity for each state, categorizing them into five groups based on the intensity level.

Among individuals aged 65 and older, the findings revealed a stronger correlation between Alzheimer’s disease prevalence and nightly light pollution than with other established disease indicators such as alcohol abuse, chronic kidney disease, depression, and obesity.

While other risk factors like diabetes, high blood pressure, and stroke did display a higher association with Alzheimer’s disease, the impact of light pollution was undeniable.

Increased vulnerability in younger people

Interestingly, this association was even more pronounced in the population under 65, indicating a higher sensitivity to the effects of nighttime light exposure. The reason behind this age-related sensitivity to light pollution remains unclear.

“Certain genotypes, which influence early-onset AD, impact the response to biological stressors which could account for increased vulnerability to the effects of nighttime light exposure,” said Voigt-Zuwala.

“Additionally, younger people are more likely to live in urban areas and have lifestyles that may increase exposure to light at night.”

Prevention and mitigation techniques

As a result of their findings, the researchers advocate for increased public awareness regarding the potential effects of light pollution.

“Awareness of the association should empower people – particularly those with risk factors for Alzheimer’s disease – to make easy lifestyle changes,” said Voigt-Zuwala. Changes may include the use of blackout curtains or sleeping with eye masks, especially for those residing in high light pollution areas.

Moreover, internal light exposure would be as significant in this discourse. Although not examined in this study, the researchers pointed out that blue light, in particular, disrupts sleep.

The usage of blue light filters, transition to warm light, and installation of dimmers could effectively reduce light exposure within households.

Alzheimer’s and the path forward

The team acknowledges that their study is based on a subsection of the U.S. population and that not everyone resides in areas with high light pollution throughout their lives.

The experts noted that further research is needed to explore the complex relationship between nighttime light exposure and Alzheimer’s disease.

As research continues to uncover the potential connections between Alzheimer’s and light pollution, experts emphasize the importance of taking preventative steps.

Communities can work to reduce outdoor light pollution by using shielded streetlights and promoting darker night skies, which may help minimize the risk of Alzheimer’s disease in the population.

On an individual level, simple adjustments such as reducing blue light exposure in the evening and prioritizing quality sleep can be vital in protecting long-term brain health.

By addressing both external and internal sources of light pollution, there is hope for mitigating one of the many factors linked to Alzheimer’s disease.

The study is published in the journal Frontiers in Neuroscience.

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