Stress Hormone Cortisol Linked to Short-Term Memory Loss in Older People

Researchers link stress hormones to short-term memory loss in older people.

Researchers at the University of Iowa found that the hormone cortisol could increase chances of memory loss in the elderly.

Cortisol helps humans deal with everyday problems and stay alert during a bad situation. However, high levels of the hormone for extended periods of time can lead to several health problems. Previous research has linked cortisol levels to obesity and high blood pressure as well.

The present study shows that the hormone even affects memory, especially in old people.

"Stress hormones are one mechanism that we believe leads to weathering of the brain," said Jason Radley, assistant professor in psychology at the UI and corresponding author on the paper, according to a news release.  

In the preliminary study, researchers linked high levels of the stress hormone to loss of synapses in the pre-frontal cortex, which is associated with short-term memories. The synapses or connections between neurons help humans process and recall information. Exposure to cortisol over a longer duration of time can snap away these synapses.

According to Radley, the study shows that treatments lowering cortisol levels in the body might help fight short-term memory losses in adults.

The study was conducted on rats. The team administered different levels of corticosterone - the hormone comparable to cortisol in humans - to different sets of rats. Since rats have smaller lifespan, a 21-month-old rat is as old as a 65-year-old human and a four-month-old rat is roughly of the same age as a 20-year-old person.

These rats were placed in a maze where they had to use their short-term memories to find food. Researchers found that old rats with high levels of corticosterone scored poorly in the test. On an average, stressed rats could get the treat only 58 percent of the time, compared to their older peers with low stress hormone levels who got it around 80 percent of the time.

The team then examined the brains of the rats and found that rats on the stress hormone had 20 percent fewer synapses in the pre-frontal cortex than their less-stressed peers.

The study is published in the Journal of Neuroscience.