The symphony of brain waves during sleep orchestrates memory and the progression to Alzheimer's disease
Recent discoveries by GIGA researchers published in eLife could make it possible to detect individuals at risk of developing Alzheimer's disease at a very early stage, to include them in clinical projects and, in the long term, to better manage them to prevent or delay the disease.
t has long been known that sleep is important for memory. More recently, research has shown that sleep may contribute to the changes in brain structure that lead to Alzheimer's disease. Sleep is involved in the elimination of residual brain function, including the proteins that are thought to underlie Alzheimer's disease. The accumulation of these proteins (beta Amyloid and Tau) in turn disrupts sleep in a bidirectional relationship.
Researchers from the Cyclotron Research Centre/In Vivo Imaging of the GIGA Institute at ULiège (GIGA-CRC-IVI) have just demonstrated that the coalescence of cerebral oscillations during sleep is linked to the early accumulation of beta-amyloid protein in the brain and to memory. Sleep spindles and slow waves are the two dominant oscillation types in "slow wave" sleep, which constitutes about 70% of total sleep time. Both oscillations are involved in the recovery functions of sleep and memory consolidation function of sleep. The team of Dr Gilles Vandewalle and his colleagues at GIGA-CRC-IVI has just shown us that the precise coupling of spindles and slow waves is altered when amyloid beta protein begins to accumulate in people aged 50 to 70 years without any cognitive problems. If the spindles arrive too early on the slow waves, it is an indication that there is more amyloid protein in the brain. Results also show that if the spindles arrive too early on the slow waves, the memory performance of the volunteers measured two years later will be poorer. This coupling, therefore, has a predictive value for the cognitive future of an individual and could therefore contribute to pathological ageing.
“Medical science is still largely at a loss when it comes to Alzheimer's disease, for which there is no curative solution. However, it is known that the processes that lead to this disease, i.e. the accumulation of 'toxic' proteins for the brain and the loss of synapses, begin decades before the onset of symptoms. The challenge of current clinical trials is therefore to test in at-risk individuals, detected as far in advance of the disease as possible, whether a drug or behavioural intervention can prevent or delay the onset of symptoms” says Gilles Vandewalle.
The research of GIGA-CRC-IVI, conducted in collaboration with researchers from the University of Montreal and published in eLife, sheds new light on the link between sleep, cognition and Alzheimer's disease. It could allow early detection of individuals at risk of developing the disease so that they could be included in clinical projects and ultimately to better manage them to prevent or delay the disease. Further research will show whether improving sleep quality can help slow down the process or even reverse it.
Timely coupling of sleep spindles and slow waves is linked to early amyloid-β burden and predicts memory decline, Daphne Chylinski1, Maxime Van Egroo1, Justinas Narbutas1,2, Vincenzo Muto1, Mohamed A. Bahri1, Christian Berthomier3, Eric Salmon1,2,4, Christine Bastin1,2, Christophe Phillips1,5, Fabienne Collette1,2, Pierre Maquet1,4, Julie Carrier6, Jean-Marc Lina6, & Gilles Vandewalle1*, eLife – Tue May 31st 2022
1 GIGA-Cyclotron Research Centre-In Vivo Imaging, University of Liège, Liège, Belgium.
2 Psychology and Cognitive Neuroscience Research Unit, University of Liège, Liège, Belgium.
3 Physip SA, Paris, France.
4 Department of Neurology, University Hospital of Liège, Liège, Belgium.
5 GIGA-In Silico Medicine, University of Liège, Liège, Belgium.
6 Centre for Advanced Research in Sleep Medicine, CIUSSS-NÎM – Hôpital du Sacré-Coeur de Montréal, Montréal, QC, Canada
The study was supported by funds from the FNRS, ULiège, the Fédération Wallonie-Bruxelles, the Fondation Recherche Alzheimer, the FEDER European fund and the Fondation Léon Fredericq