Behavioural effects of brain injury

Behavioural changes after brain injury are many and varied. Some appear to be an exaggeration of previous personality characteristics, while others may seem completely out of character for that person. 

This page gives information on some of the most common behavioural effects of brain injury:

Our Psychological effects of brain injury (PDF) and Managing anger after brain injury (PDF) booklets provides more detail, and the Headway helpline will be happy to talk through any specific questions you may have. 

It is important to be sensitive to extreme behavioural changes after brain injury, as they may indicate a developing mental illness. Our Mental health and brain injury (PDF) factsheet provides more information on this topic. 


A common change early in recovery is disinhibition, that is, loss of control over behaviour, resulting in socially inappropriate behaviour. This ranges from a tendency to divulge personal information too freely, to disturbing and unpredictable outbursts of uncontrolled rage.

Common complaints include a tendency to make tactless remarks, to laugh inappropriately, and to be over-familiar towards others. A major area of difficulty, especially early in recovery, is that of sexual behaviour - making inappropriate sexual advances or remarks. Abusive or crude language may cause offence and be acutely embarrassing for relatives or in social situations. Most people gradually regain control over their behaviour, but those with a severe injury may remain impulsive and/ or inappropriate in their actions.

A few people never regain adequate control over their behaviour, remaining unpredictable, aggressive and reliant on others to exercise a degree of control over their behaviour. 


A person with a brain injury may tend to speak or act without thinking about the possible consequences of their behaviour. This can lead to embarrassment in social situations, such as if they say an inappropriate remark without thinking that it might upset the person they are speaking to. Or in other circumstances it can lead to practical difficulties, such as if they agree to do a task that they are not realistically able to complete, or if they spend more money than can be afforded. 

Obsessive behaviour

A person may become obsessive or fixated on certain thoughts or behaviours after a brain injury. For instance, they may be afraid that their possessions will be stolen and subsequently check their belongings repeatedly, or they may insist on a particular routine or things being done in a certain way. 

Irritability and aggression

Perhaps the most common behavioural change after brain injury is that of increased irritability. People with a brain injury are often impatient, intolerant of others' mistakes, and easily irritated by interruptions, such as noise from children or machinery, which disrupt their concentration. They are frequently reported to be short tempered, for example when things do not work out as expected or where there are differences of opinion with family or work colleagues. Where this is associated with poor behavioural control, it may result in outbursts of verbal or physical aggression. 

"Anger is one of the many emotions which can be expressed differently, or be less controlled following a brain injury.  Many factors may underlie the changes including (but not limited to) damage to the frontal lobes and limbic system, and overstimulation.  It is also important to consider the impact of factors such as social circumstances, previous personality, and the balance between current demands and resources. 

"Developing an understanding of what is going on for each individual is essential in order to direct the type of support and intervention required. Whilst hints and tips can certainly be useful, there is no one strategy which will work for everyone.  Neuropsychologists may be in a position to assess and advise. 

"As well as being distressing and confusing for the person themselves, altered emotions can have a significant impact on those close to them. Support should therefore be directed towards both the individual and their family.  Sometimes developing the understanding of others (and altering their responding) can be the key to moving forwards."

- Dr Gemma Elliot, Clinical Neuropsychologist and Trustee of Headway Lincolnshire.

Apathy and loss of initiative

Some people may become passive, unresponsive and lacking in initiative after brain injury. They may appear unconcerned and even unaware of their difficulties, especially in the early stages of recovery. Others may appear interested and have good intentions to carry out activities, but are unable to organise themselves and initiate action. This may happen to any of us when feeling depressed, but for the person with a brain injury, this can result directly from the injury itself rather than solely as a result of depression. 


People may also become egocentric after brain injury, tending to be self-centered and appearing not to consider the feelings or needs of their family and friends. In adversity, it is most common for anyone to tend to focus on their own needs, but this can be greatly exaggerated for a person with a brain injury. Cognitive impairments can mean that they are oblivious to, or unable to appreciate, others' points of view, and they may be unaware of the needs of others.