Prior to cognitive problems sleep disruptions are early warnings of AD
Previous studies have linked loss of sleep and brain plaques, a marker of Alzheimer’s disease in mouse models as from the Washington University School of Medicine in St. Louis, last year. This study was among the first to link sleep problems and Alzheimer’s through studies of sleep in mice genetically altered to develop Alzheimer's plaques as they age.
This new study is among the first to test Aβ deposition in preclinical AD, prior to the appearance of cognitive impairment, is associated with changes in quality or quantity of sleep, according to the study’s abstract. Amyloid beta (Aβ) is a peptide of 36–43 amino acids that is processed from the Amyloid precursor protein (APP). Aβ is the main component of deposits found in the brains of patients with Alzheimer's disease.
For this cross-sectional study conducted from October 2010 to June 2012, researchers recruited general community volunteers from the University's Charles F. and Joanne Knight Alzheimer's Disease Research Center, age range 45 to 75 and had normal cognitive function at the time of recruitment.
As a part of other research at the center, scientists already had analyzed samples of the volunteers' spinal fluids for markers of Alzheimer's disease. The samples showed that 32 participants had preclinical Alzheimer's disease, meaning they were likely to have amyloid plaques present in their brains but were not yet cognitively impaired.
All participants had worn an Actiwatch 2 or Philips Respironics, actigraph which continuously measures activity or movement. Participants were instructed to wear an actigraph on the nondominant wrist for 14 days and to push a marker on the actigraph whenever getting in and out of bed.
Also, all participants had filled out a sleep diary each morning. The sleep diary had asked questions of the participants; naps the previous day, sleep latency, nighttime awakenings, wake time, and open-ended comment.
Dr. Yo-El Ju, MD, assistant professor in the department of neurology, sleep medicine specialist and first author of the study, referring to the actigraph’s commented "Most people don't move when they're asleep, and we developed a way to use the data we collected as a marker for whether a person was asleep or awake.” "This let us assess sleep efficiency, which is a measure of how much time in bed is spent asleep."
Researchers found that participants who had preclinical Alzheimer’s disease (early phase of the disease before signs and symptoms appear) had poorer sleep efficiency (80.4 percent) compared to participants without markers of Alzheimer’s disease (83.7%). On average, those with preclinical disease were in bed as long as other participants, but they spent less time asleep. They also napped more often.
"When we looked specifically at the worst sleepers, those with a sleep efficiency lower than 75 percent, they were more than five times more likely to have preclinical Alzheimer's disease than good sleepers," said Dr. Ju.
In their conclusion the research team writes “Amyloid deposition in the preclinical stage of AD appears to be associated with worse sleep quality but not with changes in sleep quantity.”
Dr. David Holzman, MD, the Andrew B. and Gretchen P. Jones Professor and Chairman of Neurology, Professor of Developmental Biology, Associate Director of the Alzheimer's Disease Research Center, and a member of the Hope Center for Neurological Disorders and senior author stated "This link may provide us with an easily detectable sign of Alzheimer's pathology.” "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."
In closing Dr. Ju states "We think this may help us get a better feel for the way this connection flows ; does sleep loss drive Alzheimer's, does Alzheimer's lead to sleep loss, or is it a combination?" "That will help us determine whether we can change the course of disease with pharmaceuticals or other treatments."
The other researchers were; Jennifer S. McLeland, MSW, MA; Cristina D. Toedebusch, BS; Chengjie Xiong, PhD; Anne M. Fagan, PhD; Stephen P. Duntley, MD; John C. Morris, MD
Information on Alzheimer’s disease and dementia can be found online at the Alzheimer’s Association website.
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