Chronic sleep disturbances could trigger early Alzheimer's onset

Researchers have suggested that people, who experience chronic sleep disturbance - either through their work, insomnia or other reasons - could face an earlier onset of dementia and Alzheimer's.

Domenico Pratico, professor of pharmacology and microbiology/immunology in Temple's School of Medicine, who led the study, and his team looked at longitudinal studies which indicated that people who reported chronic sleep disturbances often developed Alzheimer's disease.

For the study, they used a transgenic Alzheimer's mouse model that begins developing memory and learning impairment at about one year-the equivalent of a human that is mid-50-60 years in age-and at 14-15 months have the typical human brain pathology of Alzheimer's, including amyloid plaques and tau protein tangles, the two major brain pathological/lesion signatures for the disease.

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.

Pratico said that at the end of the eight weeks, when they tested the mice for memory, the group which had the reduced sleep demonstrated significant impairment in their working and retention memory, as well as their learning ability.

The researchers then examined the mice's brains to look at the different aspects of the Alzheimer's pathology - mainly the amyloid plaques and tau protein tangles.

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