A cardinal feature of Alzheimer disease is the way beta-amyloid—generally a metabolic waste product—clumps to form amyloid plaques. Now a National Institute on Alcohol Abuse and Alcoholism (NIAAA) study indicates that sleep may be an important link in that process. The researchers found that losing just 1 night of sleep led to an immediate increase in beta-amyloid.
Researchers used positron emission tomography to scan the brains of 20 healthy volunteers, aged 22 to 72 years, after a night of rested sleep and after being awake for 31 hours. They found beta-amyloid increases of about 5% after the sleep deprivation in the thalamus and hippocampus, regions especially vulnerable to damage in the early stages of Alzheimer disease, the researchers say. The study participants with larger increases also reported worse mood after sleep deprivation.
It is important to note, the researchers add, that the link between sleep disorders and Alzheimer risk is considered by many scientists to be bidirectional, since elevated beta-amyloid also may cause sleep disturbance.
It is unknown, the researchers say, whether the increase in beta-amyloid in the study participants would subside after a night of rest.