As we age, some systems in the body don’t work as well. Eyesight weakens, there can be some minor age related memory loss and many people move a little slower and don’t stay as active. Sleep disturbances are common as well, but recent research shows that sleeping patterns could be an indicator of another problem seen in the elderly: dementia. Currently estimates put the number of people dealing with some form of dementia at about 46 million globally. In the United States, there are approximately 5 million people who have been diagnosed with the most common form of dementia, Alzheimer’s disease (AD) The numbers are expected to rise, with dementia cases tripling by the year 2050.
There is no cure for Alzheimer’s and no known cause. A new study conducted by researchers at Boston University however suggests that people who spend more than 9 hours a day sleeping could be at as significantly higher risk for developing dementia. The study, published in the February 22, 2017, online issue of Neurology®, the medical journal of the American Academy of Neurology, suggests that when older people start to require more sleep, it could signal degeneration of brain tissue.
Study author Sudha Seshadri, MD, of Boston University School of Medicine in Boston, Mass., and Fellow of the American Academy of Neurology explained, “We found that when older people transitioned from regularly sleeping less than nine hours to sleeping more than nine hours, they had an increased risk of developing dementia 10 years later. We also showed that those who had regularly slept more than nine hours in the past and simply maintained that level of sleep did not have an increased risk.”
Data for the study was taken from the Framingham Heart Study (FHS). The FHS is a large cohort study that started in 1948 with 5,209 men and women between the ages of 30 and 62 living in the town of Framingham, MA, just a few miles west of Boston. While the original goal of the study was to look at cardiovascular health and risk factors, the large amount of data that has been collected has been useful in other research projects. For the study on sleep patterns and dementia Dr. Seshadri’s team looked at those within the study who had developed dementia. In total there were 234 participants, with an average age of 72. 181 of those patients had an Alzheimer’s diagnosis. When asked about sleeping patterns, 96 participants reported sleeping more than nine hours a night. 75 study members reported sleeping less than that, but gradually coming to need more than 9 hours of sleep a night. In the group of men and women used to getting nine or more hours of sleep the rate of dementia was 10%. In the group who reported an increased need for longer periods of sleep, the rate of dementia was twice that, at 20%.
Cognitive testing and MRI scans showed differences in brain aging as well as brain volume. Seshandri stated, “The difference in scores on tests of processing thoughts was the equivalent of about 12 years of aging, and the difference in brain volume was the equivalent of about five years of aging. These estimates are based on small numbers and are not precise, but they give you some context for the size of the difference between those who slept longer and those who did not.
Education was a factor as well. Participants who slept longer also tended to have mild cognitive impairment and lacked a high school diploma. Seshandri summed it up saying, “Together, these results suggest that if someone is sleeping longer, it may be an early marker of neurodegeneration. Unfortunately, it is likely that any efforts to reduce their amount of sleep would not lower their risk of dementia.”
The study was not perfect however. Sleep data was self-reported by study volunteers and the sleep totals were not separated out into uninterrupted night sleep and shorter daytime naps. The team at Boston University plans to do more research to firmly establish the connection between sleep and dementia. Take a look at the video about the study.