People with Alzheimer’s disease are known to have disturbances in their internal body clocks that affect sleep/wake cycle and may increase their risk of developing the disorder. Now, new research published in JAMA Neurology indicates that such circadian rhythm disruptions also occur much earlier in people whose memories are intact but whose brain scans show early, preclinical evidence of Alzheimer’s disease.
Previous studies conducted in people and in animals have found that levels of amyloid fluctuate in predictable ways during the day and night. Amyloid levels decrease during sleep, and several studies have shown that levels increase when sleep is disrupted or when people don’t get enough deep sleep.
The researchers tracked circadian rhythms in 189 cognitively normal, older adults with an average age of 66. Of the participants, 139 had no evidence of the amyloid protein that signifies preclinical Alzheimer’s. Most had normal sleep/wake cycles, although several had circadian disruptions that were linked to advanced age, sleep apnea or other causes.
But among the other 50 subjects — who either had abnormal brain scans or abnormal cerebrospinal fluid — all experienced significant disruptions in their internal body clocks, determined by how much rest they got at night and how active they were during the day. Disruptions in the sleep/wake cycle remained even after the researchers statistically controlled for sleep apnea, age and other factors.
By tracking activity during the day and night, the researchers could tell how scattered rest and activity were throughout 24-hour periods. Subjects who experienced short spurts of activity and rest during the day and night were more likely to have evidence of amyloid buildup in their brains, the researchers said.
Paper: “Circadian Rest-Activity Pattern Changes in Aging and Preclinical Alzheimer Disease”
Reprinted from materials provided by Washington University School of Medicine.