Last Updated May 27, 2011 11:30 AM EDT
In the study, published in Proceedings of the National Academy of Sciences, volunteers were shown a series of pictures of objects and later shown a second set of images and were asked if they remembered seeing the images before. The researchers also tracked their brain activity using magnetic resonance imaging. The young adults were good at distinguishing images they'd seen before from those they hadn't, suggesting that they created a clear memory for each image they viewed.
But the older people were not as good at it--and their brain activity in the memory center was less active. Unlike their younger counterparts, they didn't create a completely new memory for each image. In fact when the images were similar, they kind of blurred together in the subject's minds. The older adults were not good at what's called pattern separation or distinguishing between similar things or experiences.
Tara Parker Pope explained pattern separation further in her Well blog,
There are many different types of memory processing, of course, but one of the more important for everyday functioning is pattern separation. "Take breakfast," Dr. Yassa [the lead author] said. Most of us follow a routine and eat much the same thing at the same time for breakfast most days, he said. But each morning's meal is unique and should produce a unique set of memories. "You need to be able to separate those memories and keep them apart," Dr. Yassa said. "Otherwise they can override one another and confuse things."
If you drive to work, you need to remember where you parked your car every day, unless you use the same spot. If you don't create a brand new memory each day, you'd be confused after work when it was time to find your car. This happens more commonly when we get older and may explain why we forget where we left our keys, whether we took our vitamins on a particular day, or even whether we locked the door when we left the house.
The Only Solution
As of now, the only thing that is thought to prevent the decline of pattern separation is exercising. It has been found to create new brain cells in the memory processing area of the brain called the dentate gyrus. Last year, a mouse study found that exercise enhanced pattern recognition in the animals.
So if you want to preserve your brain's ability to put down memories, make sure you're doing the minimum recommended exercise, which is 30 minutes of moderate-intensity exercise five days a week (or half that if it's vigorous like running) and muscle strengthening activities twice a week.
You can also make an effort to create a new memory of things you tend to forget. So if you take calcium vitamins every day, don't just take it mindlessly, but think about where you are standing, what you're taking it with (water or juice) and other sensory information so it's distinguishable from every other day of the year.