Recently, a new study has linked higher levels of the stress hormone cortisol to short-term memory loss in older adults. Scientists from the University of Iowa have published a study in the Journal of Neuroscience demonstrating this idea. The team specifies that although small amounts of cortisol are important for us to survive as a species by making us more aware in the moment, excessive amounts of the hormone can lead to problems with digestion, anxiety, weight gain, and high blood pressure over time.
This particular study is the first to focus on cortisol’s effects on the prefrontal cortex, which controls short-term memory. Researchers used twenty-one-month-old rats in the study because they are the rodent equivalent to roughly sixty-five-year-old humans, and cortisol starts to create memory lapses in humans at that age. They then compared the older rats to four-month-old rats, which equates to a 20-year-old human. The two groups were then categorized by the natural levels of cortisol they produced. Once the rats were separated, they were put inside a T-shaped maze that required the use of short-term memory to navigate. If the rats could remember the direction they had turned at the top of the T 30, 60, or 120 seconds prior and turn the opposite way, they were given a treat.
Across the board, the rats’ memory decreased the longer they had to wait to run in the maze again, as expected given the task is supposed to measure short-term memory. However, the older rats did indeed perform the worst overall. Specifically, older rats with high levels of the stress hormone were able to choose the correct direction 58% of the time, while older rats with high levels of stress chose the right direction 80% of the time.
In addition, when researchers examined samples of tissue from the prefrontal cortexes of the rats, they noted that rats that performed poorly had both smaller synapses and 20% less than the other groups. They stated these findings demonstrate memory loss because synapses help us retain information. If they erode and vanish as a result of long-term contact with cortisol, short-term memory is likely compromised. In addition, old rats with low-stress levels were found to have performed almost as well in the maze as the younger rats.
As a result of the experiment, the team suggests that short-term memory can be retained in old age by prescribing treatments that lower cortisol levels. People who experience naturally high levels of stress and those who have been exposed to chronic, long-term stress, such as that occurring from a traumatic event should be particularly careful. Although research into aging is expensive and time-consuming, the team is confident that their study will inspire other scientists to look into the possible causes of short-term memory loss in older individuals.
If you believe you or a loved one are experiencing short-term memory problems, schedule a consultation today with New York Neurology Associates. If you would like to schedule an appointment or check for availability, book online or call 212 987-0100.