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Cognitive effects of brain injury

The cognitive effects of a brain injury affect the way a person thinks, learns and remembers. Different mental abilities are located in different parts of the brain, so a brain injury can damage some, but not necessarily all, skills such as speed of thought, memory, understanding, concentration, solving problems and using language.

Our range of publications give much more detailed information on the effects of brain injury. They are available to buy from our online shop. Use the links on the right to go to the online shop homepage, or straight to relevant publications.

The cognitive system can be divided up into six separate areas:



Memory is not one thing or one skill on its own. It is easily damaged by brain injury because there are several structures within the brain that are involved in processing information, storing it and retrieving it. Damage to those parts of the brain on which these abilities depend can lead to poor memory.


Amnesia literally means 'a lack or an absence of memory'. In practice, few people forget everything, so amnesia usually refers to a failure of some part of the memory system.

Post-Traumatic Amnesia (PTA)

PTA occurs in the temporary period immediately after the accident such that the person seems relatively alright, but everyday memory for events or conversations is not working. Our factsheet 'Post Traumatic Amnesia' gives more information - you can download it now from our Factsheets page.

Retrograde and anterograde amnesia

Information from before the brain injury may be forgotten. For most people with brain injuries this gap in memory from before the injury will range from a few minutes to a few months. This memory loss from before the injury is known as retrograde amnesia. Memories laid down well before the period of retrograde amnesia are likely to be retained well.

Problems with memory for information learned after the injury are known as anterograde amnesia, and for most
people these problems are likely to cause more problems than the memory loss that predates the injury.

It is sometimes said that people with memory problems do not remember in order to protect themselves from some kind of emotional trauma. While it is true to say that there can be psychological causes for amnesia it is found that these are rare, despite its frequent occurrence in films, plays and novels.

Short-term memory loss

Short-term memory loss is the most common and troublesome type of memory problem. This can manifest itself in a variety of ways. Examples of this are forgetting what has been just said, having difficulty in learning a new skill, repeating the same question over and over, forgetting people's names, getting details mixed up, forgetting a change in routine and forgetting where things have been placed. There is no magic answer to improve this type of memory problem, and rehabilitation will try to help a person cope using tried and tested strategies. Memory is not like a muscle that can be developed just by stretching it.

Further information

Our booklet Memory problems after brain injury discusses this subject in more detail. It also includes a range of practical strategies for coping with and managing memory problems. You can buy this booklet through our online shop.

Our Coping with memory problems after brain injury - practical strategies factsheet includes some useful guidance to help live with memory problems after a brain injury.

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Attention and Concentration

A reduced concentration span is very common after head injury, as is a reduced ability to pay attention to more than one task at the same time. These problems are usually caused by damage to the frontal lobe.

Attentional problems tend to get worse when the person is tired, stressed or worried. When there are problems with concentration, other skill areas can be affected. It is difficult to follow instructions, plan ahead, be organised and so on, when there is a problem concentrating.

Working in a place with as few distractions as possible can help and, as concentration improves, distractions can be increased. In this way, someone can slowly learn to concentrate better in a world which is crowded with distracting sights and sounds.

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Speed of Information Processing

Slowing down the speed at which the brain performs the task of information processing is often due to diffuse axonal damage caused by a shake up of all of the pathways the brain uses to transmit messages. This results in problems such as not understanding fast speech, being unable to absorb instructions first time around, and not being able to quickly formulate a reply to a question.

To improve the speed of information processing, it is advisable to keep mentally stimulated at the right level to avoid overload.

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Visuospatial and Perceptual Difficulties

Organs such as ears and eyes may be working perfectly well, but the part of the brain which makes sense of incoming information from these sources may not be working properly. This gives rise to several different types of difficulty.

Problems in judging distances, spatial relationships and orientation can mean, for example, that a person may bump into furniture that they have seen, but have misjudged where it is in relation to themselves.

Sometimes a person will have a problem where one side of whatever they are looking at is not seen (visual neglect). A person may only eat half the food on their plate, or read only halfway the across the page. The ability to recognise something viewed from a different or unusual angle can be lost. This can also apply to sounds as well as vision.

Building objects or drawing them from component parts such as coloured block may be very hard.

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