Cognitive ageing: what happens to our memory when we get older?


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By: Dr Flávia S Belham*

When you think of ageing, what comes to mind? Do older people have better, worse or similar memory than younger people? Many years of research have given us the answer: it all depends on the type of memory!


Memory is the process of obtaining information from the environment, storing it, and later recalling and using it. However, memory is not a single concept; it can be divided into many sub-types. For example, when you recall your last birthday, you are using your episodic memory. When you know who the president was 100 years ago, you are using your semantic memory. And when you keep someone`s number in your head while you look for your mobile phone, you are using your working memory.


As was demonstrated by Denise Park (see Figure 1 in [1]), different types of memory have different life trajectories. For example, while working memory is commonly seen to be reduced in older adults, semantic memory is stable. That is, older adults may be slower to complete a task, but their knowledge of facts is as good as that of younger people. When it comes to episodic memory, older adults are worse when remembering details, but just as good as younger adults at remembering the gist of an event [2].
A fascinating fact about cognitive ageing is that the way we process emotions is almost opposite between younger and older people. Laura Carstensen and her research group have conducted a large number of studies and found that, whereas younger adults attend to and memorise negative events better, elderly people focus on and remember the positive things more! This is called The Positivity Effect and has been shown for images, words and personal events [3].
In my own PhD research at University College London, I found that simply instructing older adults to create a positive sentence with a common word enhances their memory for the sentences by 20 to 50%. More than that, I found that brain activity when recalling positive sentences was similar to what is seen when people are imagining things. In other words, the addition of positive emotions seems to improve our ability to create mental images, which will later facilitate memory.
This change in emotional processing happens because of one’s perception of remaining life time. While younger people can`t really see the end of their lives, older people are more conscious of that and tend to switch their attention and cognitive resources to meaningful and positive events [4].
Memory is one of our most important cognitive functions. It is crucial that the older population is able to maintain good memory for longer. Some research groups have been working with cognitive training programs, which are sets of tasks designed to boost cognitive functions. A meta-analysis by Michelle Kelly and colleagues [5] suggests that these techniques are robust in enhancing cognitive functions directly related to what was trained, but do not always improve other cognitive domains. Since the world’s population is getting older and older, it is fundamental that we keep on researching how to preserve memory in ageing so we have more functional, productive and happy people around us.
References:

  1. https://www.dialogues-cns.org/contents-15-1/dialoguesclinneurosci-15-109/
  2. https://www.ncbi.nlm.nih.gov/pubmed/19914220
  3. https://www.sciencedirect.com/science/article/pii/S2352154617300712
  4. https://www.ncbi.nlm.nih.gov/pubmed/10199217
  5. https://www.tcd.ie/Neuroscience/neil/assets/pdf/Kelly_2014.pdf

Dr Flávia Belham is Chief Scientific Officer at Seneca Learning, where she is applying experimental findings from Neuroscience to the development of learning resources learning. During her PhD in Cognitive Neuroscience at University College London (UCL), she used behavioural and brain imaging techniques to investigate how people of different ages memorise emotional events. You can contact her @FlaviaBelhamPhD.
For article in Spanish, click here.

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