Excessive exposure to city light pollution such as street lights and neon signs could increase the risk of Alzheimer’s – especially in people under 65.
Researchers studied light pollution in 48 US states and divided them into five groups based on brightness intensity.
The data was compared to medical records of people in those states, looking at known risk factors for Alzheimer’s such as high blood pressure and obesity.
Analysis suggested higher outdoor night-time light was linked to a greater prevalence of the disease.
For people aged 65 and older, it appeared to have more influence on the development of the disease than some other risk factors such as alcohol abuse, depression and obesity.
Almost one million people are already living with dementia in the UK but experts believe that a third of people affected have not even received a diagnosis yet (File)
The Alzheimer’s Society has said dementia is the biggest health and care issue of our time
But for the under-65s, it was linked to a greater risk of Alzheimer’s than any other factor in the study.
This could suggest younger people may be particularly sensitive to the effects of light at night, said the researchers at Rush University Medical Center in the US.
It is unclear why they may be more vulnerable, but it could be due to differences in light sensitivity, they added.
Dr Robin Voigt-Zuwala, first author of the study, said: ‘Nightly light pollution – a modifiable environmental factor – may be an important risk factor for Alzheimer’s disease.’
He said awareness should ’empower people to make easy lifestyle changes’ such as using blackout curtains or sleeping with eye masks.
The findings were published in the journal Frontiers in Neuroscience.
