New Links Between Alzheimer’s and Sleep Disorders

The October 2013 issue of JAMA Neurology published a study led by the Johns Hopkins Bloomberg School of Public Health that examined the correlation between Alzheimer’s disease and sleep disorders. The researchers studied 70 adults, whose average age was 76, and determined that the adults who slept approximately five hours a night and those with poor sleep quality had higher amounts of a protein associated with Alzheimer’s disease than those that slept more  and had better quality sleep.  However, the researchers could not determine whether poor sleep caused the build-up of proteins or hastened the development of the disease. According to Dr. Adam Spira, the lead author of the study and an associate professor with the school’s Department of Mental Health, “These results could have significant public health implications as Alzheimer’s disease is the most common cause of dementia, and approximately half of older adults have insomnia symptoms.”  Dr. Spira further stated, “These findings are important in part because sleep disturbances can be treated in older people. To the degree that poor sleep promotes the development of Alzheimer’s disease, treatments for poor sleep or efforts to maintain healthy sleep patterns may help prevent or slow the progression of Alzheimer disease.”

This study parallels another study  recently published in the journal Science.  The study,  funded by the National Institute of Neurological Disorders and Stroke (NINDS), which is part of the National Institutes of Health (NIH), suggests that a good night’s rest may literally clear the mind. In this study, researchers injected mice with beta-amyloid, a protein associated with Alzheimer’s disease, and the measured the length of time it remained in their brains during sleep and when they were awake. Beta-amyloid disappeared faster when the mice were asleep, which suggests sleep normally clears toxic molecules from the brain. A related article suggests that researchers believe that all the cleaning activity is one of the reasons the brain uses about as much energy while in sleep mode as compared to wake mode. Sleep is known to perform many critical functions, including consolidating memories and recharging cells, but this is the first time sleep has been linked with cerebral rubbish removal.

The CDC estimates 5 million Americans aged 65 years or older have Alzheimer’s disease, and this number may go as high as 13.8 million unless more effective ways to prevent and treat the disease are identified and implemented. Alzheimer’s disease ranks as the 6th leading cause of death among adults aged 18 years or older, and is the 5th leading cause of death for adults aged 65 years or older.  In 2010, the direct and indirect costs of dementia among those aged 70 and over totaled an estimated $159 billion to $215 billion, depending upon the monetary value placed on informal care. The direct health care expenditures were significantly higher than for cancer and were similar to those for heart disease.

According to the Alzheimer’s Association, people with Alzheimer’s experience problems with sleeping or changes with their sleep patterns. Sleep changes associated with Alzheimer’s may include difficulty sleeping, daytime napping, and shifts in sleep-wake cycles. The Alzheimer’s Association estimates that affected individuals spend approximately 40 percent of their time in bed at night awake and a significant part of their daytime sleeping; in extreme cases sleep patterns are completely reversed. The NIH strongly urges those suffering changes in their sleep patterns not to use sleep medications. Sleep medications generally do not improve overall sleep quality for older adults and they are associated with an increased risk of falls and confusion, consequently negating any benefits derived from the medication.