Traumatic Brain Injury and Ageing

Written by Sofia Amirbayat
Edited by Rowena Fletcher-Wood

The brain is a complex organ that has a natural ability to adapt and change with time; it is made of about 100 billion neurons, able to connect to each other in networks and pathways. What makes these networks is our lived experiences with the world and people. When a baby is born, the brain has specialised areas for sensory perception, but doesn't have many learned pathways yet and is very open to learning and forming networks.

Lateral View of the Brain by BruceBlaus [CC BY 3.0], via Wikimedia Commons.

There are several interesting parts of the brain, but perhaps the most interesting is the prefrontal cortex. The prefrontal cortex is involved in higher cognition, planning, decision making, personality and social behaviours. There is one category of cognition that is often associated with the prefrontal cortex: executive functions – a group of complex mental processes and cognitive abilities such as working memory, impulse inhibition, and reasoning.

Patients with prefrontal cortex damage can experience blunted emotional responses, which may negatively affect their ability to make decisions. This can lead to them failing to see the consequences of their actions (what we call “thinking ahead”).

How does the structure of the brain change as you age?

Midlife Matters

The really exciting thing about psychology is there are a huge number of unknowns... but for me a really important part is understanding how high level cognition and decision making change in adulthood. - says Lily Fitzgibbon, a researcher in psychology at the University of Birmingham, who is exploring unknown pastures in psychological science.

Middle adulthood, commonly defined as your 30s, 40s and 50s, is a key time for making significant life changing decisions. It is also precisely what the Online Wisdom Lab (OWL) team at Birmingham University want to explore, and they are already underway preparing a suite of apps for members of the public to download and contribute through.

The majority of research into adult psychology is done at universities on the most readily available source of adult volunteers - university students. But perhaps this has led us astray a little, because this means that our current understanding of adult psychology is based almost entirely on the psychology of 18-21 year olds - at least until later adulthood, where some researchers have explored decline in cognitive abilities and its connections to illnesses such as Alzheimer's. Even though I like to think I was a pretty together undergraduate student, I'm not sure I'd feel represented now by the psychology of 18-21 year olds. When I was 21 I tried to take a piano hill walking. I broke into my friends' houses and left them hidden chocolate muffins. I survived for days at a time on free crisps and biscuits alone. I’m no longer the same person I was, just a few years later.

Not only this, but at 21 the human brain hasn't finished growing yet - especially the prefrontal cortex, where higher level thinking and decision-making take place. This region of the brain carries on developing into your mid-late twenties at the very least^[1,2,3].

On average, brain maturity is reached at around 22, synaptic "pruning" in the prefrontal cortex continues into the twenties and white matter volumes peak in the late thirties. Image credit: BruceBlaus [CC BY 3.0], via Wikimedia Commons

If 18-21 year olds are not fully developed, then might we be underestimating the decline of cognitive abilities in old age?

The Secrets of Ageing

Stormy weather ahead? Image credit: r000pert

At the moment at least, ageing is an inevitable part of life. And yet scientists don’t really understand how, or why, we age. It is thought that a combination of pre-programmed bodily changes and environmental issues are responsible^[1], but how these interact isn’t clear. Some researchers in this area aim to help us make better lifestyle choices^[2], such as eating more healthily or exercising more, in order to live a long and healthy life. Others meanwhile are looking for a way to stop the ageing process in its tracks^[3].

Perhaps the first question that needs answering before we can fully understand the ageing process is whether it’s something coded into our genes, or simply a case of our bodies ‘wearing out’. From an evolutionary point of view, once an animal has passed reproductive age it’s of little use, and may not be worth the food needed to keep it alive. This means it makes sense for animals to die as soon as they are no longer fertile. There have been some suggestions that human women live so long post-menopause because they were useful in helping to look after their grandchildren^[4], so their offspring were more successful. However it isn’t clear that this benefit would run to humans living as long as we do now. Another possibility is that rather than being an evolutionary advantage, ageing is purely a result of damage accumulating in our bodies - meaning that if we could prevent that damage, we may be able to extend our lifespans indefinitely.