Chronic sleep disturbance could trigger onset of Alzheimer's

http://www.eurekalert.org/pub_releases/2014-03/tu-csd031714.php

PUBLIC RELEASE DATE: 17-Mar-2014

Contact: Preston M. Moretz
Temple University

Chronic sleep disturbance could trigger onset of Alzheimer's

People who experience chronic sleep disturbance—either through their work, insomnia or other reasons—could face an earlier onset of dementia and Alzheimer's, 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.

Initially, the researchers looked at longitudinal studies which indicated that people who reported chronic sleep disturbances often developed Alzheimer's disease.

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"Surprisingly, we didn't see any difference between the two groups in the amyloid plaques," noted Praticὸ. "However, we did observe that the sleep disturbance group had a significant increase in the amount of tau protein that became phosphorylated and formed the tangles inside the brain's neuronal cells."

Tau protein acts as an important component for neuronal cell health, but elevated levels of phosphorylated tau can disrupt the cells' synaptic connection or ability to transport a nutrient/chemical or transmit an electrical signal from one cell to another, said Praticò.

"Because of the tau's abnormal phosphorylation, the sleep deprived mice had a huge disruption of this synaptic connection," he said. "This disruption will eventually impair the brain's ability for learning, forming new memory and other cognitive functions, and contributes to Alzheimer's disease."

Praticὸ said that since the sleep deprived mice developed the Alzheimer's brain pathology earlier than the mice who were not deprived, sleep disturbance acts as a trigger that accelerates the pathological process of tau becoming phosphorylated and irreversibly damaging the synaptic connection.

"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."