Deep sleep disruption linked to tau protein buildup and memory impairment

Disruption of deep sleep has been linked to a buildup of tau protein in the brain, one of the key hallmarks of Alzheimer's disease, and memory loss. Scientists from the University of California at Berkeley came to this conclusion. The work was published in the journal Nature Neuroscience (NN).

The researchers compared younger adults with participants aged 65–75 years. Using EEG, they tracked slow brain waves during deep sleep, and using PET scans, they tracked the accumulation of tau protein. In older people with more tau protein, the slow waves spread to smaller areas of the brain and were more likely to occur in isolation. The more their distribution was disrupted, the worse participants remembered new information overnight.

For some volunteers, the examination was repeated several years later. The rise in tau protein levels was accompanied by further disruption of deep sleep and memory impairment. However, changes were also observed in people without diagnosed Alzheimer's disease.

The authors note that it is not yet possible to determine which occurs first - the accumulation of tau protein or sleep disturbances. However, the results suggest that changes in deep sleep may accompany Alzheimer's-related processes long before the onset of significant symptoms.