Development in late adulthood
Development in late adulthood
Development doesn't stop as we grow older. In fact, the brain continues to develop throughout our entire life. So, we change as we grow older as well.
Traditionally, developmental psychology has been focused on child development, but recently we've been investigating more and more the elderly population. It's not coincidental because we find that the elderly population is bigger and bigger proportion of the overall population.
Any developmental changes in this group are very important to make sure that they integrate in society and function to the best of their capabilities.
Now, often changes in adulthood are for the worse. Our eyesight diminishes, we remember less, but that's not always the case. In some aspects, we actually get better over-time.
The problem is that any change that we investigate could be related to aging, is something we are interested in, but it could also be related to aging-related diseases.
Because we have no experimental control over aging, we can adjust, subtract a few years from a person and add a few years, we have no way of investigating causal relationships. The only thing we can do is make a correlation between what we know that happens at a certain age in that person and what happens at a later age in that person.
Changes in the brain
One of the major changes that happen during aging in the brain is the increase in grey matter loss. Grey matter is the area in the brain, where all the cell bodies of the neurons are, where all the complex processing is happening.
If you lose this area, you can process less rapidly. The brain is made up of this grey matter and also white matter. White matter is the axons, so the communication between neurons. It's white because it's myelinated, and myelin is white, hence the name.
One of the most obvious changes in the brain is the increase in ventricle size. Ventricles are holes in the brain that are filled with fluid, and they are there to absorb shocks, when you, for example, hit your head against the wall, they absorb part of the shock and also to transport nutrients or waste throughout the brain.
They're not necessarily directly involved in any of the processing, but of course, when the ventricles grow, there's less space for grey and white matter. They are an indication of brain matter loss.
In the brain of a young person, the ventricles are relatively small. Compared to an older individual, the ventricle size has grown rapidly. That means probably that grey and white matter is lost. The outer layer, becomes thinner, so the grey matter actually decreased. That's not something that is only present in humans, but it's also present in animals.
Age-related diseases
In age-related diseases, these changes are even more marked. In Alzheimer's disease, we see a rapid reduction in grey matter and that's over the entire brain. Some areas are more affected than others. For example, a decrease in size of the hippocampus means that the person is likely to have memory problems.
Another area that's affected is the frontal brain and the frontal brain area is involved in self-control. We might see that people with Alzheimer's are becoming less tactful when they speak to people or about people.
There are also aspects that are just changing over time as we grow older and that's just normal. One of those aspects is memory. Memory decreases as we grow older.
Testing memory
The way we could test memory is to have a list of say, 20 words and then ask people to remember as many as possible. After 5 to 10 minutes, ask them to recall as many words as they can. A middle-age person could remember 18 words from that list while someone who is in late adulthood might just remember 15 or 14. That is normal. As we grow older, we remember less but it is a definite effect of ageing.
A similar study we can do is having a drawing where people are asked to draw from memory. They're shown a drawing, and then asked to replicate the drawing. Older people generally forget to include many items in their drawing, where the drawing becomes more simplistic with less detail than the sample drawing they've been shown.
Processing speed
Another aspect of ageing is processing speed. As we grow older, we become less fast at processing certain things. When you are asked a question, it takes you longer to respond. You're not necessarily worse at responding, it's just that it takes longer.
Muscle strength and sensory processing
Another aspect is muscle strength. The number of muscle fibres and also the strength of the individual fibres decreases over time. Finally, there is a small decrease in sensory processing. Visual colours, for example, become less vivid over time, as well as odours, they become less strong. They're perceived to be less strong as we grow older.
Why do these changes occur?
These changes are all also correlated with changes in the brain. Memory changes are clearly linked to hippocampal change. Indeed, if we look at the hippocampal change over time, as people grow older, we see that there is a decrease in hippocampal volume.
The frontal brain area similarly decreases in strength or decreases in volume over time, which has an effect on processing speed. The visual cortex, for example, is relatively stable.
We see that, similarly, visual processing is relatively stable at increasing age. It's not all doom and gloom as we grow older. There are certain aspects that we actually get better at. We might get worse at memory and processing speed, but we gain certain other aspects.
Increased semantic knowledge
One of those aspects is semantic memory or semantic knowledge. Semantic knowledge is having a concept of a certain thing, the concept of a cat, for example, knowing what a cat is. We have an increasing number of concepts as we grow older.
Perhaps linked to that is the increase in vocabulary. As we grow older, we have a larger and larger vocabulary, which may explain why people in late adulthood might enjoy playing crossword puzzles.
Increased positivity
Finally, emotionality also increases over time. What I mean by that is that you're more likely to remember the positive things than the negative things. It's also easier to retrieve positive memories than negative memories. That's perhaps why it seems like older people always think that it was so much better in the past.
The specific balance between the functions that are lost and gained determines the quality of life. It's imperative that we study these changes that happen over time because we want to make sure that also the elderly function well in society.
Developmental psychology now pays attention to the elderly, where they're studied alongside child development, but also development in older age. Hopefully, that will help us to understand, not only how our child develops and grows to fit into society, but also how our grandparents can remain functioning in society
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