The research on healthy adults aged 55 years and older, published in the journal Sleep, used magnetic resonance imaging (MRI) and neuropsychological assessment to investigate changes in the brain associated with aging.
For every hour of reduced sleep duration, the researchers found an incremental annual expansion of the brain ventricles and an annual incremental decline in global cognitive performance.
The age-related brain atrophy was seen in the ventricles, a series of interconnected, fluid-filled spaces in the core of the forebrain and brainstem. (A neuroscience book published online gives more information about the ventricular system.)
“Though faster brain ventricle enlargement is a marker for cognitive decline and the development of neurodegenerative diseases such as Alzheimer’s,” the researchers say, “the effects of sleep on this marker have never been measured.”
The research paper’s results therefore add new evidence: “Each hour of reduced sleep duration at baseline augmented the annual expansion rate of the ventricles by 0.59%, and the annual decline rate in global cognitive performance by 0.67% in the subsequent 2 years, after controlling for the effects of age, sex, education and body mass index.”
The study put 66 older Chinese adults through structural MRI brain scans that measured brain volume. They also had their cognitive function tested every 2 years using neuropsychological assessments.
A questionnaire was used to record the subjects’ sleep duration. The participants came from the Singapore-Longitudinal Aging Brain Study, which has yielded evidence in numerous other published medical papers.
In the Sleep paper’s conclusion, inflammatory effects were ruled out by the Duke-NUS authors: “In healthy older adults, short sleep duration is associated with greater age-related brain atrophy and cognitive decline. These associations are not associated with elevated inflammatory responses among short sleepers.” The researchers checked this by measuring a marker of systemic inflammation, high-sensitivity C-reactive protein