Things We Don’t Know: 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

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?

As we age over 40, the brain’s neural plasticity begins to decrease, although it never completely goes away. The brain changes in various ways, such as shrinking in size, reducing neural communication in certain areas, reducing cognition function and decreasing blood flow. Factors such as exercise – both physical and mental – help to maintain neural plasticity.

Mental exercise activates the brain’s equipotentiality, a memory theory that the neighbouring area of a damaged one can take over the function of the damaged area![1] In support of this theory, we’ve discovered that memories are not localised in the brain, but spread out across different areas. Equipotentiality is activated because mental exercise increases brain chemicals and encourages the growth of neurons, which sharpens memory and enhances learning. So it’s possible to improve memory power at any age by living a healthy lifestyle! Scientists are looking into how to keep your brain sharp and delay cognitive decline with age, and what causes it to happen.

Brain plasticity is an important property and could be linked to some mental disabilities. The ability to change this property could be very beneficial to aid those with mental disabilities (i.e. for those recovering from a stroke).

Ageing

Ageing is inevitable. © r000pert (CC BY-ND 2.0) via Flickr

How does trauma change the brain?

After a traumatic brain injury, you might experience physical, emotional, behavioural, speech or cognitive changes. An example of this is short-term and working memory loss. This can make it hard to remember names or basics things, like where you put your keys; it can be permanent or temporary, and some people have to relearn everything. As a result of brain damage, the ability to process and understand information slows down, therefore some could take longer to carry out physical activities including routine activities like getting dressed or cooking, or taking more time than usual to follow instructions like in a classroom or at work. Organisation and decision-making skills can be affected; for instance, you could have trouble making and scheduling appointments and planning your day.
An example of a physical effect that can arise from traumatic brain injury is the loss of mobility. If the motor cortex is damaged, mobility may be impacted, which can lead movements to be very slow, with affect balance and upset coordination. Physical therapy can help with regaining movement and strength.

Speech can also be affected, especially if Broca’s area is injured, and where it becomes slurred; this is known as dysarthria. If people affected by brain injury experience dysarthria, they can access speech therapy, which may involve breathing and muscle exercises and repetition of words or sentences. Other cognitive problems that can occur are finding difficult to read and understand written information such as books, newspapers and magazines. The two main areas that are vital for language processing are located in the left hemisphere of the brain for most people, and are called Wernicke’s and Broca’s areas. In the past, researchers have found this out through studies on people with damage in these areas after they discovered them.

Language areas in the brain


Language areas in the brain. Public Domain.

Patients with damage to Wernicke’s area will have difficulty understanding words but will seem to speak fluently and easily. This is because this area is involved in speech production and is vital for the significance of words. However, their words will lack meaning because the ability to understand words is disturbed by damage.

On the other hand, Broca’s area is linked to the grammar and syntax of speech (the arrangement of words and phrases to create well-formed sentences in a language); therefore damage to this region can lead to hesitant, stumbling speech, and an inability to use grammar to understand a sentence, even when the meaning of the words are understood.

Words and language

Words and language. Public Domain.

More recently, researchers have found out from imaging studies that processing may be distributed across a broad cortical area network rather than divided neatly into two main sections. The initial studies on damage to Wernicke’s and Broca’s were in patients who also had damage to other regions. Patients with more focussed lesions (trauma or injury to the brain) don’t show the same level of difficulty with speech; nonetheless, it continues to be seen exactly how these distinct regions are engaged and whether our capacity to speak is spread across them or whether certain roles are concentrated in certain areas.

Brain injuries can also cause emotional changes, a change in behaviour and personality, or disinhibition, resulting in socially inappropriate behaviour; for example, saying whatever comes to mind without thinking about how it might insult the listener. This is most likely if the prefrontal cortex is damaged.

How does ageing affect recovery from brain trauma?

As you age, your brain loses its neural plasticity because the blood vessels that connect the brain to the skull – called bridging veins – shrink and become tighter, thinner, and more susceptible to damage, and the neural pathways are weaker so take longer to heal. Therefore, older people take longer to recover from traumatic brain injuries than younger people. Scientists are working to overcome these challenges and increase neural plasticity in older people to help them recover from traumatic brain injuries. However, after two years of traumatic brain injury, most people continue to show decreases in ability. According to brain recovery statistics, a person over the age of 65 that suffers from a traumatic brain injury only has a 40% chance of full recovery. Each additional year of age over the age of 65, the prognosis of a full recovery drops by 3%.

Therapists also work with the injured person in their home or community environment. Psychotherapy is a common treatment for behaviour disorders, mental illnesses, or any other psychological problems. It’s often used to treat depression following traumatic brain injury. After brain damage, emotions can range from feeling down, sad, blue or hopeless, and can fluctuate: the next moment feeling happy and cheerful!

It’s crucial for people with traumatic brain injury and their families to understand that behavioural problems are a result of the brain injury; they are not the injured person’s fault. This is sometimes difficult to understand because in general people are not educated about brain injury and its influences on behaviour.

What can be done to test for concussions effectively?

At the moment, tests for concussion leave a lot to be desired. Doctors may need to examine coordination, memory, and reflexes as well as testing for symptoms such as nausea and dizziness. One method that can be effective which is used for some circumstances is brain imaging. The reason why it is only used for some circumstances is that it is expensive and time-consuming, so can’t be used e.g. to decide if a player can go back on the pitch after a head injury during sport.

Now, researchers in Birmingham have suggested we may be able to test for small amounts of chemicals in the blood or even the breath that are released when the brain is damaged through a concussion. Another method may be using transcranial magnetic stimulation to look for differences in brain activity. However, we don’t yet know how effective these tests will be, or whether they can be made cheap, simple, and quick enough to use in places like the side of a sports pitch, where they are desperately needed.

Boxing

Boxing. Skeeze (CC0 Public Domain via Pixabay)

A second concussion is known as second impact syndrome. It occurs when the brain swells rapidly shortly after a person suffers a second impact.

Although its cause is uncertain, it is thought that the brain’s arterioles lose their ability to regulate their diameter, and therefore lose control over cerebral blood flow, causing massive cerebral edema. Most cases have occurred in young people, and it disproportionately affects teenagers. Players as young as 14 have died on the pitch after going back to play following a head injury. All documented cases occurred in people younger than 20, except in boxing. As of 2000, the syndrome had never been reported in the medical literature in anyone younger than adolescents. We don’t know why.

Our brain sends and receives signals that tell the information centres to process our experiences. But what network do these signals use to navigate the brain? Does it vary for different thoughts or actions? Why do they take the routes they do?

Though there are no definitive answers to these questions yet, a team from Indiana University, are working towards them. They believe that when signals cascade and then meet, the places where they meet are sites of higher cognitive function, required for tasks like speaking, for example. Their idea is to produce a map to work out where and which connections are made in the brain, and why. Interestingly, to build this they are using a social media model that maps non-viral forms of information spreading across Twitter! The team are also looking at the effect of brain lesions on information distribution.

The brain is somehow wired to adapt itself for critical periods in life when key inputs are being made, such as early childhood. Does this mean that a lack of exposure to key stimuli could impact brain processing development?

Tests have been done to suppress brakes on learning, but seizures can happen as a side effect. Other research has looked at producing new neurons – an ongoing challenge.

Summary

For a brain to work properly, all areas have to communicate with each other. Injuries can lead to specific problems, but the solutions are far from straightforward. However, the brain is adaptable and therefore, brain injury can be re-programmed slowly into new or repaired neural network connections. Whilst this adaptability decreases with age, scientists are working to overcome that hitch!

If you want to talk to an expert about brain injury, we recommend the NHS and Headway.

To learn more about the brain, have a look at Things We Don’t Know’s other related articles.

References

[1] Lashley, K. S. (1929). Brain mechanisms and intelligence. Chicago: University of Chicago Press.

Sofia is an A level student at Greene’s, studying Spanish, French and chemistry. Although she doesn’t study psychology, she has an interest in the subject. For returners week (that bit between AS and A2 studies), the students were asked to complete a project, and Sofia decided to turn her hand at science writing and research a new topic. This led her to traumatic brain injuries and the question of how ageing affects recovery.

Posted on: July 29th, 2019 | Categories: Education, News, Science, Tutor Articles