The connection between poor sleep,
memory loss and brain deterioration as we grow older has been elusive. But for
the first time, scientists at the University of California, Berkeley, have
found a link between these hallmark maladies of old age. Their discovery opens
the door to boosting the quality of sleep in elderly people to improve memory.
Postdoctoral fellow, Bryce Mander,
demonstrates how the sleep study was conducted.
UC Berkeley neuroscientists have found that the slow brain waves generated during the deep, restorative sleep we typically experience in youth play a key role in transporting memories from the hippocampus -- which provides short-term storage for memories -- to the prefrontal cortex's longer term "hard drive."
However, in older adults, memories
may be getting stuck in the hippocampus due to the poor quality of deep 'slow
wave' sleep, and are then overwritten by new memories, the findings suggest.
"What we have discovered is a
dysfunctional pathway that helps explain the relationship between brain
deterioration, sleep disruption and memory loss as we get older -- and with
that, a potentially new treatment avenue," said UC Berkeley sleep
researcher Matthew Walker, an associate professor of psychology and
neuroscience at UC Berkeley and senior author of the study to be published Jan.
27, in the journal Nature Neuroscience.
The findings shed new light on some
of the forgetfulness common to the elderly that includes difficulty remembering
people's names.
"When we are young, we have
deep sleep that helps the brain store and retain new facts and
information," Walker said. "But as we get older, the quality of our
sleep deteriorates and prevents those memories from being saved by the brain at
night."
Healthy adults typically spend
one-quarter of the night in deep, non-rapid-eye-movement (REM) sleep. Slow
waves are generated by the brain's middle frontal lobe. Deterioration of this
frontal region of the brain in elderly people is linked to their failure to
generate deep sleep, the study found.
The discovery that slow waves in the
frontal brain help strengthen memories paves the way for therapeutic treatments
for memory loss in the elderly, such as transcranial direct current stimulation
or pharmaceutical remedies. For example, in an earlier study, neuroscientists
in Germany successfully used electrical stimulation of the brain in young
adults to enhance deep sleep and doubled their overnight memory.
UC Berkeley researchers will be
conducting a similar sleep-enhancing study in older adults to see if it will
improve their overnight memory. "Can you jumpstart slow wave sleep and
help people remember their lives and memories better? It's an exciting
possibility," said Bryce Mander, a postdoctoral fellow in psychology at UC
Berkeley and lead author of this latest study.
For the UC Berkeley study, Mander
and fellow researchers tested the memory of 18 healthy young adults (mostly in
their 20s) and 15 healthy older adults (mostly in their 70s) after a full
night's sleep. Before going to bed, participants learned and were tested on 120
word sets that taxed their memories.
As they slept, an
electroencephalographic (EEG) machine measured their brain wave activity. The
next morning, they were tested again on the word pairs, but this time while
undergoing functional and structural Magnetic Resonance Imaging (fMRI) scans.
In older adults, the results showed
a clear link between the degree of brain deterioration in the middle frontal
lobe and the severity of impaired "slow wave activity" during sleep.
On average, the quality of their deep sleep was 75 percent lower than that of
the younger participants, and their memory of the word pairs the next day was
55 percent worse.
Meanwhile, in younger adults, brain
scans showed that deep sleep had efficiently helped to shift their memories
from the short-term storage of the hippocampus to the long-term storage of the
prefrontal cortex.
Co-authors of the study are William
Jagust, Vikram Rao, Jared Saletin and John Lindquist of UC Berkeley; Brandon Lu
of the California Pacific Medical Center and Sonia Ancoli-Israel of UC San
Diego.
The research was funded by the
National Institute of Aging of the National Institutes of Health.
Story Source:
The above story is reprinted
from materials provided
byUniversity of California - Berkeley. The original article was written by Yasmin Anwar.
Note: Materials may be edited for
content and length. For further information, please contact the source cited
above.
Journal Reference:
1.
Bryce A Mander, Vikram Rao, Brandon
Lu, Jared M Saletin, John R Lindquist, Sonia Ancoli-Israel, William Jagust,
Matthew P Walker. Prefrontal atrophy, disrupted NREM slow waves and impaired
hippocampal-dependent memory in aging. Nature Neuroscience,
2013; DOI:10.1038/nn.3324
Need to cite this story in your
essay, paper, or report? Use one of the following formats:
APA
MLA
MLA
University of California - Berkeley
(2013, January 27). Poor sleep in old age prevents the brain from storing
memories. ScienceDaily. Retrieved January 28, 2013, from
http://www.sciencedaily.com/releases/2013/01/130127134212.htm
