Brain injury is an umbrella term used to describe damage to the brain that occurs after birth. It can happen suddenly through an accident or injury, or develop as a result of illness, stroke, infection, lack of oxygen or other medical events.
The effects of brain injury vary greatly from person to person. Some changes may be physical, while others affect memory, concentration, communication, emotions, energy levels or sensory processing. Many of these experiences are not immediately visible.
Brain injury can be non-apparent
An estimated 69 million people experience a traumatic brain injury globally each year (The Lancet Neurology)
Brain injury can happen at any age and experiences vary from person to person (WHO / Headway)
Brain injury may be traumatic or acquired through injury, illness, stroke, infection or lack of oxygen (Headway)-
Fatigue is one of the most common effects after brain injury (Headway)
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Memory, concentration and processing can be affected after brain injury (Headway / Brain Injury Association of America)
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Recovery and adjustment can change over time and no two brain injuries are the same (Headway)
What is Brain Injury?
Brain injury is an umbrella term used to describe damage to the brain that happens after birth. Some brain injuries are caused by external trauma, such as a fall, road traffic collision, sports injury or assault. Others are acquired through illness or medical events, such as stroke, infection, tumour, aneurysm or lack of oxygen.
Brain injury can affect memory, concentration, communication, emotions, movement, energy levels and sensory processing. Some effects may be visible, while others are non-apparent and can be misunderstood by others.
Brain injury is not a reflection of personality, intelligence or character. Many of the challenges people face are linked not only to the injury itself, but also to how environments, systems and societal attitudes respond to them.
What causes brain injury?
Brain injury can happen for many different reasons. Causes may include:
- Traumatic causes, such as falls, road traffic collisions, sports injuries or assaults
- Stroke or interruption to the brain's blood supply
- Brain tumours
- Infections such as meningitis or encephalitis
- Lack of oxygen to the brain
- Aneurysms or other medical events
No two brain injuries are the same, and the impact can vary depending on the area of the brain affected, the severity of the injury, and the support and environments around the person.
Types of Brain Injury
Brain injury is often described in different categories. These may include:
- Traumatic Brain Injury (TBI) – caused by an external force or impact, such as a fall, collision or blow to the head
- Acquired Brain Injury (ABI) – damage to the brain occurring after birth, including from illness or medical causes
- Hypoxic or anoxic brain injury – caused by reduced or absent oxygen supply to the brain
- Stroke-related brain injury – caused by interruption to blood flow in the brain
- Diffuse brain injury – injury affecting multiple areas of the brain
Healthcare professionals will focus on the individual's experiences, support requirements and recovery rather than assuming that one type of brain injury affects everyone in the same way.
Common symptoms and signs
Experiences can vary and may change over time. They are often described in several areas:
Cognitive differences:
- Memory differences
- Difficulty concentrating or processing information
- Slower thinking or decision-making
- Difficulty planning, organising or switching between tasks
Physical and sensory experiences:
- Fatigue or reduced stamina
- Headaches
- Changes in balance, coordination or mobility
- Sensitivity to light, sound or busy environments
Communication, emotional and behavioural changes:
- Difficulty finding words or following conversations
- Changes in confidence or emotional regulation
- Anxiety, frustration or reduced tolerance of stress
- Changes in social interaction or communication style
Not everyone will experience all of these, and they may present differently for each person.
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Important note
This information is intended for awareness and education only. It is not a diagnostic tool and should not be used to identify or diagnose any condition. If you have concerns, please seek advice from a qualified healthcare professional.
Sources
World Health Organization (WHO): https://www.who.int/health-topics/neurological-disorders
The Lancet Neurology: https://www.thelancet.com/journals/laneur
Headway – the brain injury association: https://www.headway.org.uk/
Brain Injury Association of America: https://biausa.org/
Centers for Disease Control and Prevention (CDC): https://www.cdc.gov/traumatic-brain-injury/
The content on this page has been reviewed by Headway, June 2026. For further information, please visit [https://www.headway.org.uk]