UC Riverside psychologist's research team discovers sleep mechanism critical to memory consolidation and finds that Ambien enhances the process
A team of sleep researchers led by UC Riverside psychologist Sara C. Mednick has confirmed the mechanism that enables the brain to consolidate memory and found that a commonly prescribed sleep aid enhances the process. Those discoveries could lead to new sleep therapies that will improve memory for aging adults and those with dementia, Alzheimer's and schizophrenia.
The groundbreaking research appears in a paper, "The Critical Role of Sleep Spindles in Hippocampal-Dependent Memory: A Pharmacology Study," published in the Journal of Neuroscience.
Earlier research found a correlation between sleep spindles - bursts of brain activity that last for a second or less during a specific stage of sleep - and consolidation of memories that depend on the hippocampus. The hippocampus, part of the cerebral cortex, is important in the consolidation of information from short-term to long-term memory, and spatial navigation. The hippocampus is one of the first regions of the brain damaged by Alzheimer's disease.
Mednick and her research team demonstrated, for the first time, the critical role that sleep spindles play in consolidating memory in the hippocampus, and they showed that pharmaceuticals could significantly improve that process, far more than sleep alone.
In addition to Mednick the research team includes: Elizabeth A. McDevitt, UC San Diego; James K. Walsh, VA San Diego Healthcare System, La Jolla, Calif; Erin Wamsley, St. Luke's Hospital, St. Louis, Mo.; Martin Paulus, Stanford University; Jennifer C. Kanady, Harvard Medical School; and Sean P.A. Drummond, UC Berkeley.
"We found that a very common sleep drug can be used to increase verbal memory," said Mednick, the lead author of the paper that outlines results of two studies conducted over five years with a $651,999 research grant from the National Institutes of Health. "This is the first study to show you can manipulate sleep to improve memory. It suggests sleep drugs could be a powerful tool to tailor sleep to particular memory disorders."
A total of 49 men and women between the ages of 18 and 39 who were normal sleepers were given varying doses of zolpidem (Ambien) or sodium oxybate (Xyrem), and a placebo, allowing several days between doses to allow the pharmaceuticals to leave their bodies. Researchers monitored their sleep, measured sleepiness and mood after napping, and used several tests to evaluate their memory.
The researchers found that zolpidem significantly increased the density of sleep spindles and improved verbal memory consolidation.