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Trouble Sleeping Linked with Memory Problems

Renee DespresFriday, June 15, 2012 - 20:39

People who have trouble sleeping may be at higher risk of developing memory problems and developing Alzheimer’s disease later in life.

In a small study of cognitively normal people, frequent nighttime waking or lying awake at night was linked to development of the brain plaques associated with Alzheimer’s disease, according to lead author, Yo-El Ju, M.D., MD, Assistant Professor in the Department of Neurology at Washington University in St. Louis, Missouri.

These preliminary findings, which were released February 14, will be presented at the American Academy of Neurology’s 64th Annual Meeting in New Orleans during the week of April 21.

 Ju’s team tested the sleep patterns of 100 people between the ages of 45 and 80. None of the study participants had a history of dementia. However, half of the group had a family history of Alzheimer’s disease.  Researchers measured participants’ sleep patterns by with a monitor for two weeks..  Participants also kept sleep diaries and answered questionnaires. 

Researchers found that participants spent an average of eight hours in bed. But  they only spent an average of 6.5 hours sleeping, because they woke frequently for short periods at night.

Ju’s team also assessed study participants for pre-clinical signs of Alzheimer’s. Beta-amyloid plaques can begin to form long before clinical signs of Alzheimer’s disease, such as forgetfulness, disorientation, and confusion, appear. One out of four study participants had evidence of amyloid plaques.

Participants who woke up more than five times per hour were more likely to have a build up of amyloid plaque compared to those who didn’t waken as frequently.  People who spent less than 85 percent of their time in bed actually sleeping appeared to be more likely to have the markers of early stage Alzheimer’s disease than those who slept more than 85 percent of the time they spent in bed.

A build-up of amyloid plaques, which are a marker of Alzheimer’s disease, seemed to occur more when sleep is disrupted, according to Ju.

The researchers cautioned that while the association suggested between disrupted sleep and amyloid plaques is fascinating, these results do not show a cause-effect relationship between the two. Nor did the study differentiate between people whose sleep was simply disrupted and those who had sleep apnea, a condition in which. Several studies have linked sleep apnea to increased risk of Alzheimer’s and other dementias.

However, they noted, this preliminary study suggests that longer-term studies are needed, which would involve following sleep patterns over years. Such studies might help to determine whether interrupted sleep can lead to amyloid plaques or whether the brain changes in early Alzheimer’s disease leads to changes in sleep.

“Our study lays the groundwork for investigating whether manipulating sleep is a possible strategy in the prevention or slowing of Alzheimer disease,” said Ju in a statement.