Animal study suggests that stress may accelerate age-related changes in the brain
A new study published in the June 18 issue of The Journal of Neuroscience adds to a body of evidence suggesting stress may accelerate cognitive decline later in life. The study found that aged rats with high levels of the stress hormone corticosterone showed structural changes in the brain and short-term memory deficits.
While most people will experience some cognitive decline as they get older, the extent of these changes and how rapidly they progress varies greatly from one person to the next. Scientists are interested in understanding the factors that contribute to these differences. Research suggests that how the body responds to stress may be one of the factors influencing how the brain ages. Multiple animal studies have linked high levels of the stress hormone corticosterone (similar to the human stress hormone cortisol) with age-related structural and functional decline in the hippocampus, a region that plays a key role in long-term memory.
Jason J. Radley of the University of Iowa wanted to know whether exposure to high levels of corticosterone is associated with other changes in the brain and memory deficits. In the current study, he and others measured the amount of the stress hormone in the blood of young and old rats and examined cells in the prefrontal cortex, a region of the brain involved in short-term memory. The researchers found that older animals with high levels of the stress hormone had fewer connections between prefrontal cortex cells than the older animals with lower levels of the hormone. In contrast, prefrontal cortex cells appeared similar in younger animals regardless of stress hormone levels.
"Older animals with higher levels of stress hormones in their blood have 'older' frontal cortexes than animals with less stress hormones," explained Stanford University professor Robert Sapolsky, PhD, an expert on the damaging effects of long-term stress who was not involved with this study. "Thus, stress may act as a pacemaker of aging in this key brain region."
Older rats with higher levels of stress hormone displayed a 20 percent reduction in the density of dendritic spines (the small protrusions on neurons that come into close contact with other cells to form synapses, the connections between cells) relative to age-matched rats with less stress hormone.
The researchers also compared how the young and old rats performed on a simple working memory task, where the animals had to remember which arm of a two-arm maze contained a food reward following varying periods of delay. Older animals with higher levels of corticosterone made more errors when attempting to predict the location of the reward than age-matched animals with less of the stress hormone after a brief period of delay.
"These findings are not meant to indicate that high stress hormones are the only factor in determining the decline of mental abilities during aging," Radley cautioned. "Nonetheless, this study suggests that the effects of these stress hormones on the brain may be much more widespread than we previously thought."
This research was funded by the National Institute of Mental Health.
The Journal of Neuroscience is published by the Society for Neuroscience, an organization of nearly 40,000 basic scientists and clinicians who study the brain and nervous system. Radley can be reached at email@example.com. More information on aging, stress, and memory can be found on BrainFacts.org.
Emily Ortman | Eurek Alert!
Brands are Perceived in the Same Way as Faces
28.08.2015 | Leuphana Universität Lüneburg
“Bank & Zukunft 2015” trend survey highlights the need for banks to reform business models
21.08.2015 | Fraunhofer-Institut für Arbeitswirtschaft und Organisation IAO
Longer, more severe, and hotter droughts and a myriad of other threats, including diseases and more extensive and severe wildfires, are threatening to transform some of the world's temperate forests, a new study published in Science has found. Without informed management, some forests could convert to shrublands or grasslands within the coming decades.
"While we have been trying to manage for resilience of 20th century conditions, we realize now that we must prepare for transformations and attempt to ease...
A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.
The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...
A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).
Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...
In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.
These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...
Bacteria do not cease to amaze us with their survival strategies. A research team from the University of Basel's Biozentrum has now discovered how bacteria enter a sleep mode using a so-called FIC toxin. In the current issue of “Cell Reports”, the scientists describe the mechanism of action and also explain why their discovery provides new insights into the evolution of pathogens.
For many poisons there are antidotes which neutralize their toxic effect. Toxin-antitoxin systems in bacteria work in a similar manner: As long as a cell...
20.08.2015 | Event News
20.08.2015 | Event News
19.08.2015 | Event News
31.08.2015 | Awards Funding
31.08.2015 | Materials Sciences
31.08.2015 | Materials Sciences