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Light Pollution and Risk of Alzheimer’s Disease
Context:
Over the past 25 years, global artificial lighting has surged by 49%, causing the night sky’s brightness to increase nearly 10% annually, now affecting around 80% of the world’s population.
Light Pollution and Alzheimer’s Disease Risk:
Global Light Pollution Increase:
- Artificial lighting has surged by 49% worldwide in the last 25 years.
- Night sky brightness has increased by 10% annually over the last 12 years.
- 80% of the global population is affected by light pollution.
Health Impact of Light Pollution:
- Associated with sleep disorders, fatigue, anxiety, and deprivation.
- New studies suggest a link between light pollution and increased risk of Alzheimer’s disease.
Study Findings on Alzheimer’s Disease and Light Pollution:
Key Risk Factors:
- Alzheimer’s risk factors include heart disease, high blood pressure, diabetes, smoking, and alcohol consumption.
- New evidence suggests light pollution is another significant risk factor.
Research Methodology:
- Researchers used Medicare data (2012-2018) and NASA satellite maps to study light pollution’s link to Alzheimer’s.
- Data included people aged 65 and above from diverse ethnic backgrounds.
Findings for People Over 65:
- Light pollution was a stronger risk factor for Alzheimer’s than kidney failure, depression, heart failure, alcohol abuse, and obesity.
- Diabetes, high blood pressure, and stroke were still more strongly correlated with Alzheimer’s than light pollution.
Findings for People Under 65:
- Light pollution was linked to a higher prevalence of Alzheimer’s than other risk factors for this group.
- The effect was consistent across genders and ethnic groups, except for Pacific Islanders.
Sleep and Brain Health Connection:
Sleep Disruption:
- Light exposure at night interrupts sleep and affects brain function.
- Poor sleep impairs the brain’s glymphatic system, which clears toxic proteins like amyloid linked to Alzheimer’s.
Circadian Rhythm Disruption:
- Light pollution disrupts circadian rhythms, leading to inflammation and susceptibility to diseases.
- Inflammation may increase amyloid production, a protein found in Alzheimer’s patients.
Study Limitations and Broader Evidence:
- Unmeasured Variables:
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- Indoor artificial light and air pollution, both linked to cognitive decline, were not accounted for in the study.
- The study focused solely on the US population without adjusting for socioeconomic factors.
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- Support from Other Research:
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- Studies in China and Italy also found links between light pollution and cognitive decline, such as mild cognitive impairment and late-onset dementia.
- Light pollution has been connected to Parkinson’s disease as well.
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- Modifiable Risk Factor:
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- Light pollution is a modifiable risk factor for Alzheimer’s, unlike other non-modifiable factors.
- Simple solutions like blackout curtains, eye masks, and dimming lights can reduce nighttime light exposure.
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