It’s not just the fact that older people have more to remember and reminisce about, it may be that it is easier for them to recall an older memory than it is to create a new one.
When we form a new memory the information has to be received and then processed by the area of out brain called the hippocampus. As we get older, those neural pathways bringing the information to the hippocampus start to get degraded. So if there are more potholes in the road, it is harder for the brain to get the information to the processing plant to lay down a new memory.
Professor Yassa at John Hopkins University has been using 3 different forms of MRI scans (structural, functional and diffusional) to study how well different areas of the brain communicate and distinguish between old, new and similar information and the differences between the brains of younger College students and a group of 60 to 80 year olds.
What he found was that the older subjects were less able to recognise something that was similar to something they had recently seen. Images had also to be very different, to be picked up as being new. This was attributed to the older group having a more degraded pathway of the information getting to the hippocampus.
So next time you forget where you parked the car. It may not just be because you didn’t pay attention at the time, but also that your brain is relying more on previous memories of where you parked previously, which may not be of much help to you this time round!
M.A. Yassa, A. T. M., S.M. Stark, C.E.L.Stark (2011). "Age-related memory deficits linked to circuit-specific disruptions in the hippocampus." Proceedings of the National Academy of Sciences,.