Alzheimer's protein linked to memory formation during sleep

Clumps of a protein called beta amyloid in the brain are the main suspect for the cause of Alzheimer's disease, but now new research shows they may also play a role in disrupting memory in seemingly healthy adults. A brain imaging study in a small group of elderly but healthy adults linked increased levels of amyloid accumulation in the brain with disrupted deep sleep and mild memory impairment.

 Disruption in sleep-associated memory consolidation is associated with the accumulation of β-amyloid (Aβ) in the prefrontal cortex of healthy older adults, reports a paper in Nature Neuroscience. Accumulation of Aβ is already a leading candidate mechanism for memory impairment in aging and Alzheimer's disease, and this research highlights a possible role for cognitive decline related to sleep disruption in healthy aging.

Matthew Walker and colleagues studied the ability of 26 healthy adults, between ages 70 and 79, to remember word pairs before and after a night's sleep. They recorded the brain waves of participants during sleep, in addition to conducting fMRI and PET scans. Their research shows that the extent of Aβ accumulation in a brain region called the medial prefrontal cortex predicts a reduction in slow wave brain activity during non-rapid eye movement (NREM) sleep and an increase in memory impairments. The authors suggest that this accumulation disrupts slow wave brain activity during NREM sleep and that this Aβ-induced disruption, in turn, directly impairs long-term memory consolidation.

While this study cannot attribute Aβ accumulation as the causative factor in disruption of NREM sleep and memory decline, it highlights sleep disruption as an important factor contributing to cognitive decline and raises the possibility of exploring therapeutic sleep intervention to mitigate age-related cognitive decline associated with Aβ pathology.