And it’s not just about the things we do to age well, it’s also about the things we avoid.
There is a large field of research that seeks to understand the factors that cause different rates of age-related decline. In particular, scientists look at how these factors change our ability to remember and pay attention to things in everyday life. We call such changes “cognitive ageing”.
Earlier work has looked at how diet or doing physical or mental exercise (sudoku, crosswords) affects ageing. However, the amount of stress we experience over a lifetime and the impact it has on cognitive ageing has remained an under-researched area, until recently.
A lifetime of stress.
Work from our lab and from others has found that many of the negative aspects of cognitive ageing seen in older people appear to be linked to the amount of stress they have experienced in their life. We began by measuring the number of stressful events experienced over the lifetime. (WATCH: Feeling stressed? Here are some quick yoga moves to practice on your lunch break. Post continues after the video.)
We looked at a number of factors ranging from experiencing a major illness or losing a loved one, to changing one’s social habits or moving home. Old people who have experienced a lot of stress tend to perform worse on cognitive tasks than those who experienced less stress.
Crucially, old people who haven’t experienced much stress in their life perform just as well on cognitive tasks as young people.
This suggests that stress has a big impact on mental ability and that the effect of this only appears in old age. Indeed, young people did not differ from each other in their performance of cognitive tests whatever their life experience of stress had been. (Post continues after the gallery.)
Not only that but the patterns of brain activity of the people taking part in our study reflect the same effect: older people (aged 60 to 80) who have experienced less stress have brain activity similar to that of younger people.
However, when it comes to the brain activity of those elderly people who have led stressful lives, we find something very different going on.
This brain activity may give us some clues as to what’s going wrong and where in the brain it is happening. For instance, depending on the task involved, we can see that a significant amount of stress in a person’s lifetime can affect their ability to hold items in their short-term memory and can also reduce their ability to stop irrelevant thoughts from interfering with this process.