Whether chronic sleep disturbances are caused by work or insomnia, they could result in an earlier onset of dementia and Alzheimer’s disease, according to a new pre-clinical study by researchers at Temple University.

“The big biological question that we tried to address in this study is whether sleep disturbance is a risk factor to develop Alzheimer’s or is it something that manifests with the disease,” said Domenico Praticò, professor of pharmacology and microbiology/immunology in Temple’s School of Medicine, who led the study.

How a lack of sleep relates to Alzheimer’s disease

Initially, the researchers looked at longitudinal studies which indicated that people who reported chronic sleep disturbances often developed Alzheimer’s disease. They then used a transgenic Alzheimer’s mouse model, mice that begin developing memory and learning impairment at about one year – the equivalent of a human who is mid-50-60 years in age.

The eight-week study began when the mice were approximately six months old, or the equivalent of an adult human in their 40s. One group of mice was kept on a schedule of 12 hours of light and 12 hours of darkness, while a second group was subjected to 20 hours of light and only four hours of darkness, greatly reducing their amount of sleep.

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Reduced sleep impairs working and retention memory and learning ability

“At the end of the eight weeks, we didn’t initially observe anything that was obviously different between the two groups,” said Prof Pratic?. However, when they tested the memory of mice, the reduced sleep group demonstrated significant impairment in their working and retention memory and learning ability.

Researchers found that the sleep disturbance group had a significant increase in the amount of tau protein. Although tau protein acts as an important component for neuronal cell health, elevated levels of phosphorylated tau can disrupt the cells’ synaptic connection. This disruption eventually impairs the brain’s ability for learning, forming new memory and other cognitive functions, and contributes to Alzheimer’s disease.

“We can conclude from this study that chronic sleep disturbance is an environmental risk factor for Alzheimer’s disease,” he said. “But the good news is that sleep disturbances can be easily treated, which would hopefully reduce the Alzheimer’s risk.”

Source: Temple University via ScienceDaily

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