Injury to the frontal lobes after a traumatic brain injury (TBI) can affect the area of the brain that normally controls our impulses.
This inability to control urges can lead to impulsive and inappropriate social behaviour. For example, a previously shy person may become quite extroverted and talkative. In a more severe case, a normally reserved person might make crude or sexually inappropriate comments to strangers.
When others don’t understand how brain injury can cause impulsive behaviour, it often leads to rejection and criticism. Social isolation often results, as existing relationships break down and there is an inability to form new ones.
Apart from a TBI involving the frontal lobes, impulsivity can also result from a brain injury caused by alcohol and other drugs, dementia, other types of brain disorders and mood disorders.