Sleep disturbance increases the risk of developing Alzheimer's disease.
"There is previous evidence that sleep can affect the development or progression of Alzheimer's disease in many ways," said Dr. Barbara Bendlin, MD, of the University of Wisconsin at Madison.
Her research was published in the July issue of the American Journal of Neurological Sciences. The researchers found a link between sleep disorders and indicators for Alzheimer's disease in the spinal fluid of subjects.
The study population is 101 people with an average age of 63, who have normal memory and thinking skills but are at risk of developing Alzheimer's disease.
Some of these were carriers of genes that either have parents with Alzheimer's disease or that increase the likelihood of Alzheimer's disease, called Apo Fat Protein E or APOE.
The researchers sampled the subjects' spinal fluid samples and examined the quality of their sleep.
People with sleep disturbances and frequent naps often showed signs of Alzheimer's disease in the spinal fluid compared to people without sleep disorders. The researchers found amyloid, tau, brain cell damage and inflammation.
Amyloid is a protein that can turn into plaques, and tau causes protein tangle. Plaque and protein tangles are hallmarks of the brain in Alzheimer's patients.
"Whether sleep affects the onset of this disease or whether the disease affects the quality of sleep is still unclear," Dr. Benlinlin said. He also said that more experiments are needed to reveal this relationship.