A new study finds high levels of cortisol, stress hormone, to be linked with increased risk of short-term memory loss in elderly. Researchers from the University of Iowa strengthen previous researches that a prolonged increase in the production of cortisol can have negative health consequences.

Researchers carried out the study on rats. They studied a group of rats that were in age group 4 to 21 month-old. First thing that researchers observed in rats was whether they naturally had high or low level of corticosterone (a hormone comparable to cortisol in humans).

After knowing the hormone level, researchers placed the rats in a T-shaped maze requiring them to use their short-term memory. Researchers offered treats but to get them, rats had to recall the direction they had turned at the top of T just 30, 60 or 120 seconds before and turn the opposite way each time they ran in the maze.

Older rats having high corticosterone levels performed the worst. They were able to choose the right direction just 58% of the time when compared with 80% of time in rats having lower levels of corticosterone.

Researchers explained the reason behind the same. A rise in the amount of cortisol led to the slow loss of synapses in the prefrontal cortex, the region of the brain that is responsible for short-term memory. Synapses are such connections that help humans process, store and recall information.

After carrying out the study, researchers got to know that rats with higher level of corticosterone had 20% few synapses than those having lower levels of corticosterone. With advancement in age, long-term and repeated exposure to cortisol can lead synapses to shrink and disappear.

Short-term memory loss can be prevented or slowed in elderly by providing them treatment that reduces the level of cortisol in their body.