Poor Sleep Patterns May Signal Alzheimer's

Patients in an ongoing study on memory and aging with preclinical Alzheimer’s disease were more likely to have low sleep efficiency and to nap frequently.

Poor sleep quality could be an early indication of Alzheimer’s disease, according to the results of a study published online on March 11, 2013, in JAMA Neurology. Many established Alzheimer’s patients suffer from disrupted circadian rhythm and sleep disturbances, but this study is among the first to make the connection between poor sleep patterns and early Alzheimer’s disease in humans. The study was conducted by researchers at the Washington University in St. Louis Knight Alzheimer's Disease Research Center.

The researchers studied 145 volunteers aged 45 to 75 who were cognitively normal at the time of enrollment. The participants were drawn from an ongoing long-term study on memory and aging. Thirty-two (22.5%) of the participants had preclinical Alzheimer’s, meaning that they showed no signs of cognitive impairment but likely had beta-amyloid plaques as indicated by cerebrospinal fluid amyloid-beta 42 (CSF Aβ42) levels of 500 pg/mL or less. Participants kept sleep diaries for 2 weeks, noting sleep-related information, including what time they went to sleep and arose and when they took naps.

Sensors on participants’ wrists tracked their activity levels and sleep efficiency, a measure of how much time they actually spent asleep when they were in bed. The results showed that participants with preclinical Alzheimer’s had the lowest levels of sleep efficiency and napped more. Preclinical Alzheimer’s participants were also more likely to take naps 3 or more days per week. However, the researchers did not find an association between quantity of sleep and amyloid deposition.

“This link may provide us with an easily detectable sign of Alzheimer’s pathology,” senior study author David M. Holtzman, MD, head of the department of neurology at Washington University, said in a press release. “As we start to treat people who have markers of early Alzheimer’s, changes in sleep in response to treatments may serve as an indicator of whether the new treatments are succeeding.”

Next, the researchers plan to conduct studies on younger participants, which may help determine causation—whether sleep loss contributes to Alzheimer’s or Alzheimer’s causes sleep loss. Knowing which way the connection goes, “will help us determine whether we can change the course of disease with pharmaceuticals or other treatments,” said lead study author Yo-El Ju, MD, an assistant professor of neurology at Washington University, in the press release.

Ms. Wick is a visiting professor at the University of Connecticut School of Pharmacy and a freelance writer from Virginia.