Analysing sleep may help us monitor brain changes associated with Alzheimer’s disease
Sleep may contain information to help us understand and potentially monitor some of the brain changes associated with Alzheimer’s disease. Researchers from the University of Camerino, in collaboration with the University of Bristol, have shown that poor sleep may not simply be a consequence of the disease. It may also actively contribute to its progression.
During sleep, the brain carries out essential maintenance processes. It consolidates memories, regulates its own activity, and engages mechanisms that help it maintain normal function. Understanding how these processes change in Alzheimer’s could therefore provide important insights into the disease itself.
The research team focused their investigation on infraslow oscillations. These very slow rhythms help organize sleep spindles, brief bursts of electrical activity in the brain that also play an important role in memory-related processes. The team analysed sleep in people with Alzheimer’s disease or mild cognitive impairment on the Alzheimer’s spectrum, and in cognitively healthy individuals of a similar age.
They found that in people with Alzheimer’s, oscillation strength was approximately 27% lower than in cognitively healthy individuals. Previous studies suggested these oscillations may be linked to systems regulating brain function, particularly a region of the brain responsible for producing noradrenaline.
During sleep, noradrenaline helps regulate blood vessel function in the brain. It also impacts mechanisms that promote the movement of cerebrospinal fluid. This contributes to the removal of waste products from the brain. Disruption of this natural brain “clearance” system could contribute to the accumulation of beta-amyloid, one of the proteins involved in Alzheimer’s disease.
Professor Michele Bellesi, research group lead, said:
“Sleep is not a passive state, but a period during which the brain undergoes highly organized physiological dynamics.
“Our findings suggest that, by learning to observe these dynamics with greater precision, we can gain information about the functioning of brain systems that we know are involved in Alzheimer’s disease.”
The relationship between sleep oscillations and biological markers of disease measured in the blood was also something the team explored. People with stronger oscillations tended to have a better beta-amyloid profile.
Other features of the oscillations were associated with markers of neuronal injury and, to some extent, with the ability to retain information learned before sleep. Taken together, these findings suggest that analysing infraslow oscillations during sleep may provide useful information about biological processes associated with Alzheimer’s disease.
Professor Bellesi added:
“The broader message of our work is that sleep may contain information about the disease that we have so far only partially learned how to access.
“Recording sleep is not simply about measuring how long or how deeply someone sleeps. It means observing the brain as it spontaneously moves through different physiological states.
“Learning to read these signals could help us better understand the relationship between sleep and Alzheimer’s and, ultimately, develop new ways of monitoring brain health over time.”
The sleep data used in this study was collected through the Remote evaluation of sleep to enhance understanding of early dementia (RESTED) study, a UK observational research programme investigating sleep disturbance and biological rhythms in people with cognitive impairment and dementia. RESTED uses wearable technologies to monitor sleep and brain activity at home, helping researchers better understand how sleep, memory and biological processes change in conditions such as Alzheimer’s disease.
