In a brain imaging study of 70 adults, researchers at Johns Hopkins investigated the impact of sleep on the accumulation of beta-amyloid plaques, a hallmark of Alzheimer’s Disease. Both the amount of sleep and sleep quality were examined for their potential contributions to beta-amyloid plaque buildup.
The participants in this study were adults whose age ranged from 53 to 91 years old, with an average age of 76. These individuals were part of a longer longitudinal brain imaging study, and their earlier MRIs were used as a reference when the presence of beta-amyloid was measured. All of these adults were community dwelling and, when originally recruited, none showed any signs of cognitive impairment or neurological disease.
Beta-amyloid plaques will build up over time, long before any clinical symptoms of Alzheimer’s appear, so researchers expected to find beta-amyloid even in the absence of clinical symptoms of Alzheimer’s or dementia. Each participant reported on their sleep patterns, and underwent a PET scan after being administered a marker that reveals the presence of beta-amyloid plaque deposits in the brain. At the time of the PET scan, one participant met criteria for dementia, and three met criteria for mild cognitive impairment.
Of the 70 participants, 24 showed elevated levels of the marker for beta-amyloid. Turning to the impact of sleep, researchers found that both shorter sleep duration and poorer quality of sleep were associated with a greater amount of beta-amyloid present. Sleep quality here was measured on a five-point scale ranging from “very sound or restful” to “very restless” and this didn’t include trouble falling asleep or waking up during the night. Trouble falling asleep and waking up during the night were also measured. No relationship was seen between waking up at night and beta-amyloid build-up. Although the relationship of trouble falling asleep to beta-amyloid buildup did not reach statistical significance, it was close to the threshold for statistical significance. These findings were not affected by removing the individuals with mild cognitive impairment or dementia from the analysis.
This research suggests that interventions to improve or maintain healthy sleep among older adults could play a role in preventing or slowing the onset or progress of Alzheimer’s Disease. This research may also have significant public health implications, since over half of older adults report having insomnia symptoms.