The effects of brain Injuries

Brain injuries affect each person differently. Depending on the type of brain injury, the area of the brain affected and the extent of the injury, the effect of brain injury will vary from person to person. A person with a brain injury does not necessarily show all of the effects described below.


When a brain injury is very severe, a person may slip into a state of coma. When someone is in a coma they are unconscious and although they may look as though they are asleep, they cannot be woken up. Someone in a coma is not able to respond, or speak or follow commands such as “open your eyes” or “squeeze my hand”. They will not be able to move but may have some reflex muscle jerks or twitches.

A person can be in a coma for hours, days or several weeks, or longer. Coming out of a coma happens gradually and slowly, so at first they will drift in and out of coma. Nobody can predict how well they will come out of a coma because it depends on where in the brain the injury has occurred and the severity of the injury, amongst other factors. A person may come out of a coma with a combination of physical, cognitive and psychological difficulties that need special attention.

If the brain is so badly damaged the body needs to rest to allow the brain to heal, doctors will sometimes deliberately put someone in a coma, called a drug-induced coma. A drug-induced coma or controlled coma allows the body to switch off and focus on the healing process. Some people continue to show only very basic responses and will move from a coma into a minimally conscious state; others may recover quite well.

People often wonder if someone in a coma can hear or feel. And although it is impossible to know (because those who come out of a coma do not remember what it was like) it is recommended that we speak with and act around them as if they can hear, feel and understand.

Minimally Responsive State / Minimally Conscious State

This term is used when a person is no longer in a coma and is more aware of themself or others around them. They can open their eyes, have a sleep-and-wake cycle and are able to respond with some movement such as blinking, but this is inconsistent or minimal. They sometimes appear to be tracking (following someone or something with their eyes). Someone can remain in a minimally conscious state for a very long time and may never come out of it, which means they will need a permanent high level of care.

Post-Traumatic Amnesia

Post–traumatic amnesia (PTA) is a phase people go through following a significant brain injury, when they are confused, disoriented and have trouble with their memory. They may not be able to recall their date of birth, or may not know where they are or what has happened. When left alone they could be at risk of wandering and may be unable to find their way home or they may do risky things like leave on the oven in the kitchen.

People in PTA will be tested on a daily basis with a test called the Westmead PTA scale. This test has 12 questions, some concerning orientation such as “what day is it?”, or “what year is it?”; other questions assess memory such as remembering objects or faces. This test is repeated each day and a score of one point is given for every correct answer. A person is considered to be emerging from PTA when their scores go up but they have to score 12 out of 12 three times in a row to be considered out of PTA.

Sometimes it is possible for someone to be oriented but still get the memory component of the test wrong, which tells us that he or she is not able to lay down new memories. Although most people come out of PTA eventually there is no set time for this because each person is different and each head injury heals at a different rate. Some people are in PTA for a few days or weeks; others for much longer.

Physical effects of brain injury

Depending on the affected area of the brain and the severity of injury, a person may experience physical effects such as:

  • Weakness of one or more limbs. In some cases, a person may experience paralysis or the inability to move one side of their body, which is called hemiplegia. Having difficulty moving both upper and lower limbs is called a quadriparesis.
  • Difficulty with coordination or precise, fine-tuned movements.
  • Difficulty with balance, for example being unable to sit unsupported, stand up without help or walk without help. Sometimes losing balance means that the person is at a risk of falls and may need a walking aid.
  • Difficulty with high or low muscle tone, or with ‘switching-on or switching-off’ muscles. When there is a problem with low muscle tone, a person may have difficulty using a limb; for example a low-toned arm may hang lifeless next to the body and cannot be used for reaching or supporting. When there is a problem with high tone, a person may not be able to use a limb properly because the muscles tighten up, pulling their arm or leg into awkward and maybe painful positions. People with very high muscle tone may develop a condition called spasticity, which causes muscles to seize up, be resistant to stretching and to cause stiffness in the limb. Spasticity goes hand in hand with exaggerated reflexes and spasm, or violent and painful muscle jerks.
  • Difficulty with swallowing, speech or vision.
  • Difficulty with sensation or feeling in one or more parts of the body, for example not being aware where the arm is without looking or having difficulty feeling touch, pressure, hot or cold.
  • Having difficulty with toileting - lacking the feeling to control bladder or bowels.
  • High levels of fatigue, which is different from being tired after a long day’s work. This fatigue is more of a mental fatigue, making the person unable to concentrate or participate because the brain shuts down.

Cognitive effects of brain injury

Cognitive effects of brain injury may include:

  • Poor memory, especially short-term memory. Memory problems may include the inability to lay down new memories and/or retrieve them when they are needed.
  • Poor reasoning skills - not being able to weigh up several options and choose the best option. Being unable to make choices.
  • Poor problem solving skills - unable to analyse a problem and find solutions to solve that problem.
  • Poor attention span - not able to divide attention or not able to concentrate on something. Being easily distracted.
  • Poor safety awareness or insight into their limitations.
  • Poor judgement - not seeing the consequences of a chosen behaviour.
  • Poor initiation - requiring prompting to start or complete tasks or activities.

Psychological effects of brain injury

Psychological effects of brain injury may include:

  • Inappropriate behaviour – being unable to judge right from wrong such as making inappropriate comments or showing inappropriate behaviours. This may include inappropriate sexual behaviour such as exposing themself in public, or touching other people inappropriately or making sexual inappropriate remarks. Other inappropriate behaviours may be interrupting other people’s conversations, making bad jokes or rude or socially unacceptable comments or inappropriate laughter. Demonstrating these behaviours may be embarrassing for family and friends and may cause a person to become isolated.
  • Violent and aggressive behaviour – being unable to control emotions, resulting in verbal or physical aggressive behaviour such as swearing, shouting, hitting out, biting, spitting, punching or throwing objects.
  • Emotional disregulation - being unable to control emotions such as happiness and showing excessive laughter or giggling, or showing excessive sorrow such as crying.
  • Being more at risk of being depressed, paranoid, anxious, or showing signs of being disconnected from reality.
  • Difficulty with detecting others’ emotions; for example not noticing that someone close to them is upset or angry, or not showing interest in other people’s emotions or being able to adapt their behaviour to other people’s emotions. This detachment from other people’s emotions can cause a lot of stress and disappointment in relationships. It may change someone’s relationship completely and may cause rifts in partnerships.
  • Communication problems, such as having poor social skills. That could mean not greeting someone when entering a room or saying thank you, or taking turns in a conversation. Communication problems may also include not finding the right things to say, and having difficulty with expressing wants and needs or feelings.

People who have a brain injury may have various physical, cognitive and psychological problems which will need to be addressed by a team of professionals including physiotherapists, occupational therapists, psychologists and speech language therapists. Each problem will have an overlapping effect; for example not being able to use muscles properly to form words and speak, or being unable to remember the right words to describe something may cause someone to become frustrated and could lead to aggressive outbursts when others cannot understand them. Most effects will therefore need a team approach.

Learn more about the
brain and what it does
ABI Rehab
When damage to the brain happens immediately as a direct result of an injury it is called primary brain damage.
Learn more about the
brain and what it does
ABI Rehab
We need to know what a healthy brain looks like and how it works, before we can understand what can go wrong when it is injured.
Learn more about the
effects of brain injuries
ABI Rehab
A person with a brain injury does not necessarily show all of the effects described below...
Determining the severity
of brain injury
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Although some of the brain damage happens at or around the time of injury, further damage happens in the hours and days after...