Friday, September 25, 2009

Sleep Loss & Alzheimer’s Disease

A new study provides some of the first indications that chronic sleep loss could play a role in the development of Alzheimer’s disease.

The researchers analyzed the levels of “
amyloid beta” in the brains of mice. Amyloid beta is a protein fragment.

The study reports that the accumulation of amyloid beta in the brain is a hallmark of Alzheimer's disease; the mice in the study were genetically engineered to develop the disease.

Results show that brain amyloid beta levels correlated with wakefulness. Levels increased at night when the mice were mostly awake; they decreased during the day when the mice were mostly asleep.

The study also found that brain amyloid beta levels increased during chronic sleep deprivation; mice that stayed awake longer had levels that were 25 percent higher.

“We may need to prioritize treating sleep disorders not only for their many acute effects but also for potential long-term impacts on brain health," senior author Dr. David M. Holtzman said in a Washington University School of Medicine in St. Louis news release.

The researchers also report that brain amyloid beta levels increased when they injected orexin into the brains of the mice; the levels decreased when the mice were injected with a drug that blocks the orexin receptors.

Orexin is a protein that helps regulate the sleep cycle; it is also called hypocretin.

"Orexin or compounds it interacts with may become new drug targets for treatment of Alzheimer's disease," said Holtzman.

But orexin inhibitors may not be a viable treatment option, cautions a Science News
article. The drugs may cause severe sleepiness.

Research has found that that people with the sleep disorder narcolepsy lack brain cells that make orexin. Narcolepsy involves repeated episodes of excessive daytime sleepiness.

In August the Sleep Education Blog
reported that treating obstructive sleep apnea with CPAP therapy may slow the cognitive decline of people with Alzheimer’s disease. OSA is more common between middle age and older age; symptoms of Alzheimer’s disease tend to appear after the age of 60.

Get sleep tips for older adults on

No comments:

Post a Comment