Lack of sleep is linked to Alzheimer's disease
Poor sleep may increase the chances of people at risk of Alzheimer's developing the disease, a study has shown.
Scientists conducted spinal fluid tests on 101 people with an average age of 63 who had a family history of Alzheimer's or carried a gene linked to the condition.
Participants who reported the worse sleep quality or suffered from daytime drowsiness had more biological markers for Alzheimer's than those without sleep problems.
The researchers looked for signs of beta-amyloid, clumps of toxic brain protein linked to Alzheimer's, and "tau tangles", knots of protein within nerve cells also associated with the disease.
"Previous evidence has shown that sleep may influence the development or progression of Alzheimer's disease in various ways," said lead scientist Dr Barbara Bendlin, from the University of Wisconsin-Madison in the US.
"For example, disrupted sleep or lack of sleep may lead to amyloid plaque build-up because the brain's clearance system kicks into action during sleep.
"Our study looked not only for amyloid but for other biological markers in the spinal fluid as well."
Not everyone with sleep problems in the study had abnormalities in their spinal fluid, the researchers pointed out.
For example, there was no link between biological markers for Alzheimer's and obstructive sleep apnoea.
The results, reported in the journal 'Neurology', remained the same after taking into account factors such as medication use for sleep problems, level of education, depressive symptoms or body mass index.
"It's still unclear if sleep may affect the development of the disease or if the disease affects the quality of sleep," Dr Bendlin added.
"More research is needed to further define the relationship between sleep and these biomarkers.
"There are already many effective ways to improve sleep. It may be possible that early intervention for people at risk of Alzheimer's disease may prevent or delay the onset of the disease."