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There are about 1.4 million people living with a brain injury in the UK at a cost to the economy of £15 billion per annum. This figure is based on premature death, health and social care costs, continuing disability and lost work contributions.
What is an acquired brain injury?
An acquired brain injury is a brain injury that is not present at birth but happens at a later stage in a person’s life. An acquired brain injury is not an uncommon occurrence with around 350,000 people admitted to hospital every year with this type of injury. This is usually as a result of a traumatic head injury or a stroke. It can also be as a result of other diseases, drug or alcohol use or the brain being starved of oxygen.
The effects of acquired brain injury can range from extremely mild, to completely debilitating. Even after a mild head injury, brain functioning can be affected temporarily. This is called concussion.
This can lead to symptoms such as headaches, dizziness, mood swings, anxiety, depression, fatigue, irritability and problems with memory. Most people with a mild head injury will be symptom free within weeks; however, some people can take much longer to fully recover. The more severe the injury is, the more serious the symptoms are likely to be.
People with more severe brain injuries are likely to have more complex, long-lasting symptoms which can include:
- Changes in behaviour and personality.
- Difficulties in their existing relationships or ability to form new ones.
- Being unable to lead an independent life.
The brain is a complex organ that controls thoughts, memory, emotion, touch, motor skills, breathing, vision and hunger. It is the part of the body that interprets signals and sends instructions to the rest of the body. Every sense we have relies completely on the brain functioning well. This means that damage to the brain can affect every part of the body.

What causes an acquired brain injury in adults?
An acquired brain injury is damage to the brain that happens after birth. The symptoms depend on which brain area is affected and the severity of the injury.
Some of the causes of acquired brain injury can include:
- A lack of oxygen to the brain – This is called anoxic brain injury. An example of this could be brain injury caused by nearly drowning.
- Disease – This could include Alzheimer’s disease, dementia, cancer, multiple sclerosis or Parkinson’s disease. For further reading about dementia, please see our knowledge base.
- A stroke – A stroke is a serious and life-threatening medical condition that happens when the blood supply to part of the brain is cut off. For further reading about strokes, please see our knowledge base.
- A physical injury – This could happen due to an impact or blow to the head, which may occur in a car accident, for example, a sporting accident, a fight or a fall.
- Alcohol or drug use – This can poison the brain. For further reading about how drugs and alcohol affect mental health, please see our knowledge base.
The most common types of acquired brain injury in adults
There are several possible causes of an acquired brain injury. A traumatic brain injury is where the brain is injured as a result of a trauma or injury to the head.
Examples of a traumatic brain injury include:
- A road traffic accident.
- A fall.
- A violent assault.
- An accident in the workplace.
- An accident at home.
Other forms of an acquired brain injury can include:
- A tumour.
- A stroke.
- Brain haemorrhage.
- Encephalitis (inflammation of the brain usually caused by an infection).

What are the effects of an acquired brain injury?
Different parts of the brain control different parts of the body. Depending on which part of the brain is injured and how serious the damage is will determine how the person is affected and how they will present. Injuries to the front, back, left or right of the brain all have very different effects. Within the brain there are lots of complex, subtle parts which can be damaged and cause problems.
Brain injuries usually result in some form of cognitive impairment, affecting memory function, thought processes, attention span, understanding and communication skills. In some cases, this may resolve partly or fully in time. The cognitive effect of a brain injury affects the way the person learns, remembers and thinks about things.
Some of the cognitive effects of a brain injury can include:
- Loss of language.
- Problems with memory.
- Problems with visual-perceptual skills.
- Reduced concentration abilities.
- Reduced motivation.
- Difficulties processing information.
- Impaired reasoning skills.
- Difficulties with empathy.
Changes in behaviour and personality are common in people with certain types of brain injury. Personality changes after brain injury are some of the most difficult symptoms to deal with for both the person with the brain injury and their family members. A brain injury can make patients suddenly angry and aggressive, or even cause them to feel nothing at all.
The location of the brain injury can change how the person behaves. An example of this is the orbitofrontal cortex which helps control impulsive behaviour and this plays a role in someone’s empathy towards others. If this area becomes damaged, the person may struggle to empathise with other people and might engage in more reckless, risk-taking behaviour.
To people who know them, they may seem like they have a different personality altogether post-injury. A head injury can also affect a person’s mood and emotions.
This can make them seem more depressed, angry or irritable than they were pre-injury, causing others to believe that the person has had a change in personality. Treating the emotional and behavioural effects of a brain injury can often help the person return to their old self again.
Emotional and behavioural changes after a head injury can include:
- Severe mood swings – Also known as emotional lability, emotional reactions can be extreme and the changes in emotional state can occur quickly.
- Aggressive behaviour – This is the most common change in personality after suffering an acquired brain injury. Research has shown that around 30% of people who have suffered an acquired brain injury report that they feel increased levels of anger and will display symptoms of aggression. This is thought to be caused by damage to the brain’s impulse control centre, being more susceptible to overstimulation and fatigue.
- Flat effect – This is reduced emotional expressiveness after a brain injury. An example of this may be someone being unable to show emotion through facial expressions or appearing less engaged or less interested in other people or things they once enjoyed. While brain injury can cause symptoms of apathy, it is important to remember that most patients with flat effect do still care about their loved ones but have lost the ability to express their feelings.
- Egocentric behaviour – Many acquired brain injury patients seem to develop a more self-centred personality which is caused by damage to the frontal lobe. Areas of the frontal lobe contribute to a person’s ability to empathise. When this area becomes damaged, this can impact a person’s ability to empathise, leading to egocentric behaviour.
- Obsessive behaviour – This may cause distress when their routine changes or it may cause them to continuously talk about the same subject and struggle when the topic changes. They may get stuck in certain patterns of thought or activities and they may be unaware of this and unable to change it. This is thought to be caused by reduced cognitive flexibility. Cognitive flexibility allows people to move between different tasks and change their ways of thinking in order to solve problems.
- Disinhibition – This is the loss of control over behaviour which can result in socially inappropriate behaviour.
- Impulsiveness – This may mean that the person with the brain injury speaks or acts without understanding the possible consequences of their behaviour.
When someone suffers a brain injury, they will usually lose consciousness; this may be for a few seconds, a few weeks or even long term. Consciousness happens when the cerebral hemispheres interact with an area of the brain stem called the ascending reticular activating system. Receiving an injury to these areas causes decreased consciousness or even coma.
There are different levels of coma, which can range from a very deep coma, where the patient shows no response or awareness whatsoever, to a shallower coma, where the patient responds to stimulation by movement or sounds or even opening their eyes. Even shallower levels can occur, where the patient is able to make some response to speech or communicate in some other way.
The level of coma that someone is in is usually assessed by the Glasgow Coma Scale (GCS). GCS is a simple technique which gives a rating on the severity of the coma. It assesses the patient’s ability to open their eyes, move and speak. Their score is calculated by adding up the scores from the different categories.
A person’s recovery from being in a coma is a gradual process. The longer someone is in a coma, the more risks there are associated with having long-term issues such as physical disabilities.
After being in a coma, a person may enter what is called, post-traumatic amnesia. Patients may present as being agitated and aggressive during this time.
The symptoms of having post-traumatic amnesia can include:
- Confusion, distress, agitation, anxiety.
- Aggression.
- A tendency to wander.
- Inability to recognise familiar people.
Post-traumatic amnesia may be short-lived or in more extreme cases, may last for weeks or months.
In rare but serious cases, a person with an acquired brain injury may be in a vegetative state. This means that although they come out of the coma, they have no awareness of themselves or their surroundings. If their condition persists for more than four weeks, they will be classed as being in a continuing vegetative state.
If their condition continues for 12 months after having a traumatic brain injury or for 6 months after having a non-traumatic brain injury, they will be classed as being in a permanent vegetative state. It may be possible to gain a court order at this stage in order to withdraw treatment if the person is still showing no signs of recovery.
A minimally conscious state is where someone will show distinct but minimal signs of awareness. They may not remain responsive for any length of time or in any kind of predictable way. People usually enter a minimally conscious state after being in a vegetative state.
Locked-in syndrome is where a person is aware of themselves and their surroundings, but they are unable to move or speak. People with locked-in syndrome are often able to move their eyes and eyelids and can communicate in this way. This is a very rare condition.
Treatments for acquired brain injuries in adults
Diagnosing a brain injury will require a combination of medical assessments and investigations. There are various tests available, including X-rays and CT brain scans which can help pinpoint the exact areas of the brain that are damaged. In some cases, surgery may be required.
Medical professionals treating someone with a suspected brain injury will need to know about how the injury occurred and the person’s medical history and symptoms, and they will complete a physical examination. This will include shining a light into the patient’s eyes in order to assess their consciousness, cognition, and control over movement and sensation in different areas of the body.
The most important thing initially will be to medically stabilise the person with the brain injury, and then the long-term recovery and rehabilitation can begin. The focus in treating an acquired brain injury is the cognitive, physical, emotional or behavioural impairments that have caused the changes in the functioning of the brain. The treatment plan will depend upon the type of injury and how severe it is.
Treatment for an acquired brain injury will include treatment for the injury itself or the medical condition which has caused the brain injury. Treatment for an acquired brain injury will usually involve an assessment and treatment in a hospital.
This may be in an intensive care unit, stroke unit, or specialist brain injury department. Some brain injuries can be managed on more general medical wards depending upon the nature of the injury and the hospital setting. Some injuries may be managed with medications and monitoring.
Rehabilitation is an important part of the recovery process from an acquired brain injury. The purpose of rehabilitation is to help people to recover as much as possible and to be as independent as possible. It isn’t possible to predict how much time someone will need in rehabilitation. With a severe brain injury, this can take many months.

Support available
Changes in a person’s behaviour and personality can be very difficult and even frightening for the person with the injury, and for friends and family to experience.
Some important tips that may help include:
- Identify the triggers for the person with the brain injury – Most personality changes occur because the person has lost their ability to problem solve. If you know what their triggers are, you may be able to prevent the difficulties from occurring in the first place.
- Learn behavioural strategies – Cognitive behavioural therapy (CBT) can help in learning new ways to cope and can also help in teaching empathy if this is something that has been lost. For further reading about CBT, please see our knowledge base.
- Acknowledge the loss – Acquired brain injuries can change people, sometimes long term. It is important to acknowledge how difficult this is and the loss you feel, both as the person with the injury and as the loved one.
Seeing your loved one in a distressed, agitated, delusional or aggressive state can be very difficult, but it is important to try and stay as calm as you possibly can. Seeing other people distressed and not being able to understand why may add to the confusion and distress the person with the brain injury is feeling.
Their brain may be struggling to cope with the injury, and too much stimulation should be avoided. It may be helpful to have them in a peaceful and quiet environment wherever possible.
Reducing the risk of harm is also important. This may mean having someone with the person at all times.
The injured person may ask the same things continuously, which can be very difficult. They may be persistent with delusion or inaccurate information, but it is best not to correct them or try to force them to remember something they cannot remember.
It is important to remember that the person is not in control of their actions. It may be comforting to their loved ones to realise that the person who is injured is likely to have little memory of this time while they are recovering.
Try to take time out for yourself wherever possible and seek support as a friend or family member of a person recovering from an acquired brain injury.
The Brain Injury Group provides a helpful list of charities that support people with brain injuries and their families/carers.
Click here to read about acquired brain injuries in children.