1.3 Describe possible causes of acquired brain injury

This guide will help you answer 1.3 Describe possible causes of acquired brain injury.

Acquired brain injury (ABI) happens when a person suffers damage to their brain after birth. This means the injury did not occur during birth or because of inherited conditions. Instead, it develops later during their lifetime. There are many reasons someone might develop an ABI. Some causes happen suddenly, while others develop over time.

Anyone can experience an acquired brain injury regardless of their age or background. The severity ranges from mild to severe and context always affects how people and their families are impacted.

Understanding the causes is important for supporting people with ABIs. Recognising how and why these injuries occur can also help to prevent them when possible and improve support in health and social care settings.

Traumatic Causes of Acquired Brain Injury

Traumatic brain injury (TBI) is one of the most common types of ABI. A traumatic brain injury means damage happens because of some external force or impact. This is often a blow to the head or something physically striking the skull.

Examples of Traumatic Causes:

• Falls: Slips, trips or falling from a height can lead to an impact on the head. This is common in young children and older adults.
• Road Traffic Accidents: Collisions involving cars, bicycles, or pedestrians often cause TBIs. High-speed impacts or being thrown can cause damage.
• Sports Injuries: Contact sports like rugby, boxing, football, or horse-riding carry a risk, especially if helmets or protective gear are not used.
• Assaults: Violence can lead to a blow, shaking, or weapons causing injury. This includes punches, kicking, or being struck by objects.
• Physical Abuse: Children, vulnerable adults, and older people may suffer injuries because of abuse or neglect.

The injury level depends on force, the part of the brain affected, and the presence of objects penetrating the skull.

Non-Traumatic Causes of Acquired Brain Injury

Not every acquired brain injury is the result of trauma. Non-traumatic causes damage the brain from inside the body rather than from an external force.

Common Non-Traumatic Causes:

Stroke

A stroke occurs when blood flow is interrupted to part of the brain. This starves brain cells of oxygen, causing damage or death to those cells. There are two main types:

• Ischaemic stroke: A blood clot blocks an artery to the brain.
• Haemorrhagic stroke: A blood vessel bursts and bleeds into the brain.

Both types can leave long-term effects depending on which area of the brain is affected.

Infections

Certain infections can affect the brain and result in injuries. Two examples are:

• Meningitis: This is inflammation of the protective membranes covering the brain and spinal cord, often caused by infection.
• Encephalitis: This means swelling of the brain caused by a virus or bacteria.

These infections kill or damage brain cells and can leave lasting effects, even with treatment.

Brain Tumours

A tumour is an abnormal growth of cells. When tumours grow inside the skull or brain, they put pressure on healthy areas. Surgery to remove tumours, radiotherapy, or chemotherapy may also damage brain tissue.

Hypoxia or Anoxia

Hypoxia means low oxygen levels. Anoxia means the absence of oxygen. The brain is highly sensitive to oxygen shortages. Lack of oxygen may result from:

• Drowning
• Heart attack
• Severe asthma attacks
• Suffocation
• Carbon monoxide poisoning

Damage may depend on how long brain cells are starved of oxygen.

Subarachnoid Haemorrhage

This happens when a blood vessel bursts and causes bleeding on the surface of the brain. It can be caused by trauma or may be spontaneous. Aneurysms – weak bulging blood vessels – are a key cause. The resulting pressure and swelling can cause permanent damage.

Poisoning and Substance Misuse

Some chemicals can directly harm brain tissues or affect the oxygen supply. Examples include:

• Alcohol misuse leads to brain cell damage from both toxicity and lack of nutrition.
• Illegal drug use like heroin, cocaine, or solvents can reduce oxygen or be toxic.
• Lead, mercury or other poisons can cause brain injury if ingested, inhaled, or absorbed.

Medical Conditions

Other conditions may lead to ABI including:

• Epilepsy: Prolonged seizures can reduce oxygen and damage brain tissue.
• Diabetes: Severe, untreated low blood sugar (hypoglycaemia) can cause permanent injury if not treated promptly.
• Liver or kidney failure: The build-up of toxins in the body may damage the brain (hepatic or uraemic encephalopathy).

Surgical Complications or Medical Treatment

Sometimes, surgery or medical procedures cause unintended brain injury. For instance:

• Lack of oxygen during surgery (e.g. problems with anaesthesia)
• Complications from organ transplants or open-heart surgery

Secondary Causes and Complications

An acquired brain injury may not always occur from a single event. It can also result from ongoing factors or a combination of incidents.

For example, repeated head injuries from domestic abuse or contact sports may eventually add up to significant ABI.

Secondary complications after the initial injury can worsen damage:

• Swelling in the brain (cerebral oedema)
• Repeated seizures
• Infection following an injury or surgery
• Blood clots

Prompt detection and treatment of secondary problems are important to limit the long-term impact of ABI.

Rare Causes

Some rare causes of ABI can include:

• Autoimmune diseases: The immune system attacks the brain (autoimmune encephalitis).
• Vasculitis: Inflammation of blood vessels reduces blood supply.
• Radiation therapy: Sometimes used to treat brain tumours, it can injure healthy tissue.

These are less common but may be seen in specialist health or social care environments.

Risk Factors for Acquired Brain Injury

Understanding risk factors helps identify people who may be more likely to develop ABI. Some important ones are:

• Age: Children and older people are more at risk from falls.
• Pre-existing medical conditions: Heart problems, high blood pressure, or blood clotting disorders raise stroke risk.
• Alcohol and drug misuse: These increase risks from accidents, falls, and poisoning.
• Poor safety awareness: Lack of seatbelt or helmet use increases injury risk in vehicles or sports.
• Social factors: Poverty, abuse, or neglect can increase risk, especially for children and vulnerable adults.

Removing or reducing these risks can help prevent ABIs.

How ABI Causes Affect the Person

The type and cause of ABI affects recovery, support needs, and long-term outlook.

• Traumatic injuries may cause physical, cognitive (thinking), emotional, and behavioural changes.
• Stroke is the main cause of long-term adult disability in the UK, often leaving weakness, communication, or memory problems.
• Brain infections can cause lasting learning difficulties, epilepsy, or personality changes.
• Alcohol or drug-related brain injury can damage judgment, mood, and social behaviour.

Different causes may also increase the risk of repeated injuries or complications.

The Role of Health and Social Care Workers

Understanding the main causes of acquired brain injury helps workers recognise how an injury happened, what risks may remain, and what kind of rehabilitation or support the person might need.

This enables tailored support, including:

• Preventing further injury or incidents
• Signposting to medical or mental health services
• Helping with mobility, communication, or memory aids
• Supporting people and families with emotional, social, and practical needs

Working with colleagues in hospitals, the community, and voluntary groups can help ensure each person gets support which recognises the injury’s cause and its impact.

Final Thoughts

Acquired brain injury changes lives. There are many possible causes. These range from accidents like falls and car crashes, to medical conditions such as strokes or infections, to lifestyle factors like substance misuse.

Supporting people with ABI starts with knowing how the injury happened. Each cause brings its own challenges and risks. Health and social care staff play a key part in spotting the risk factors, responding to early warning signs, and supporting people to adjust.

Prevention is as important as treatment. This can involve raising awareness, encouraging safe practices, tackling social issues, and supporting people to make healthy choices.

A good understanding of the causes of acquired brain injury gives workers the tools needed to make a positive difference. By being aware and informed, care staff can provide effective, responsible, person-centred care for people living with the consequences of ABI.