July 17, 2012
Dementia Symptoms Linked To Naps, Sleep Quality
Connie K. Ho for redOrbit.com — Your Universe Online
Even though information on Alzheimer´s is relatively sparse, researchers are ramping up their projects to find out more about the disorder. In particular, representatives at the Alzheimer´s Association International Conference in Vancouver recently stated that there´s a possible correlation between sleep quality and quantity with the risk of cognitive decline. Based on a number of studies, they concluded that naps could be linked to dementia and that the sleeping patterns of the elderly could help diagnose dementia.
According to the U.S. National Library of Medicine, Alzheimer´s is a form of dementia that affects behavior, memory, and thinking.
"The studies presented today at AAIC suggest that cognitive health declines over the long term in some people with sleep problems. The good news is that tools already exist to monitor sleep duration and quality and to intervene to help return sleep patterns to normal. If we do this, there is the possibility that we may also help people preserve their cognitive health, but that needs to be tested,” commented William Thies, the chief medical and scientific officer of the Alzheimer's Association, in a prepared statement
Past studies have shown that the risk of cardiovascular disease and type 2 diabetes can increase when individuals sleep longer or shorter than the recommended seven hours a night.
"We know that sleep patterns change as people age and that poor sleep affects overall health. What we don't know for certain is whether poor sleep has long-term consequences on cognitive function," remarked Thies in the statement.
In one study, researchers at Brigham and Women´s Hospital in Boston, Massachusetts set out on a project that analyzed data of over 15,000 participants who were involved in the Nurses´ Health Study. The individuals were 70 years of age or older during the first cognitive exam that was taken between 1995 and 2000. They took follow-up cognitive assessment every six years after the first exam. The scientists categorized the participants based on their daily sleep.
The team of investigators found that those who slept five hours or less had lower average cognition than those who had seven hours of sleep per day. As well, those who slept nine hours or more a day also had lower average cognition than those who had seven hours or day. For women specifically, the researchers saw that a change in two hours of sleep or more resulted in poorer cognitive function than those who demonstrated no change in their sleeping patterns.
After obtaining data, the researchers worked to understand the relationship between sleep duration and changes in the ration of a particular set of proteins in the brain that signal the development of Alzheimer´s. They looked at a subset of women who provided blood samples in 1999 and 2000. The team saw that the women who slept more or less than the recommended seven hours had a decline in the proteins that were studied.
"Our findings support the notion that extreme sleep durations and changes in sleep duration over time may contribute to cognitive decline and early Alzheimer's changes in older adults," explained lead author Elizabeth Devore in the statement. "The public health implications of these findings could be substantial, as they might lead to the eventual identification of sleep- and circadian- based strategies for reducing risk of cognitive impairment and Alzheimer's."
Based on these findings, researchers believe that as people age, they are more likely to have problems with sleeping like insomnia and sleep apnea. However, scientists still do not completely understand the connection between sleep problems and the risk of developing dementia or changes in cognitive function. As such, in the second study, a group of researchers from the University of California, San Francisco (UCSF) examined the cognitive function and clinical cognitive status of over 1,300 women in a multi-center study that analyzed the link between sleep quantity and declining cognitive ability. The study took place over five years and measured sleep parameters such as total sleep time, nighttime wakefulness, and sleep apnea.
"We believe that these results indicate that the relationship between sleep disordered breathing and dementia may be connected to the decrease in oxygen associated with sleep apnea and not to disrupted patterns of sleep," noted Dr. Kristine Yaffe of UCSF in the statement. "Overall, our findings support a relationship between sleep disturbances and cognitive decline in late age. They suggest that health practitioners should consider assessing older people with sleep disorders for changes in cognition."
The third study that was discussed at the conference focused on sleep quantity and how the quantity decreases as people become older. Dr. Claudine Berr of INSERM in Montpellier, France led a team of researchers to study data from the French Three-City Study, a long-term ongoing multisite study that looked at the connection between vascular disease and dementia in individuals who were 65 years of age or older. In total, 4,898 study participants completed sleep questionnaires. The researchers discovered that excessive daytime sleepiness was related to an increase in the risk for cognitive decline.
"These results suggest that excessive daytime sleepiness may be an early predictor of cognitive decline and that sleep complaints should be adequately evaluated in older persons," remarked the study's researchers in the statement.
The last study released at the conference, a project by researchers from the Washington University of School of Medicine in St. Louis, Missouri, highlighted the theory that increased production or decreased degradation of amyloid protein could lead to dementia as changes in cerebrospinal fluid (CSF) amyloid-beta 42 have been identified as biomarkers for Alzheimer´s disease. The researchers took hourly CSF and plasma samples over 36 hours from individuals with dementia, age-matched participants, and younger participants. They looked at the changes in amyloid-beta levels as well as the effects of amyloidosis on sleep patterns and aging.
"Our study suggests amyloid proteins are dynamic and regulated in a circadian pattern that is part of the normal control of amyloid-beta concentrations. Regulatory mechanisms of these proteins may be altered with aging and amyloidosis," explained Dr. Yafei Huang in the statement.
The WU researchers noted that more research needs to be done in the area.
"These findings indicate that circadian rhythms and age should be studied further and better understood as research in CSF biological markers moves forward to ensure standardized, accurate measurements of key Alzheimer's proteins for future early detection of the disease," Thies concluded in the statement.