Our frontal lobes are the part of the brain that has evolved tremendously as we separated ourselves from the animal kingdom. The large lobes are located basically in our foreheads back to the mid-temple area. The frontal lobes provide the integration of all other brain functions into a seamless whole. They allow us to do higher level thinking, those things that are above the level of animal instinct. Planning, multitasking, risk assessment and the exquisite complexities of social interaction are all handled by the frontal lobes.
Unfortunately, because of their location, the frontal lobes are often injured in traumatic events. The lobes can be pushed forward into the bony ridges in the front of the skull, resulting in bruising and tearing. Because of their size, frontal lobes can also be twisted and injured diffusely in a high speed accident. The first person to be studied after a frontal lobe injury was a miner by the name of Phineas Gage, who unfortunately had a three-foot metal rod blown through his skull. To the horror of his co-workers, he remained conscious and walked out of the mine with each end of the bar sticking out from his head. He survived and the doctors who monitored him noticed was that he "was no longer the old Phineas Gage." His treating doctor noted that "the animal side of his nature is now out of balance with his higher facilities." By this, he and others had observed that the church going, quiet Phineas Gage had turned into a loud, gambling and quite violent person after the injury. Because of this and thousands of other studies which have followed it, we now know that the actual notion of "self" resides largely in the frontal lobes. Therefore, a frontal lobe injury in a very true sense, changes an individual from their former self to a new person, and in the vast majority of cases, an inferior person.
I like to analogize a frontal lobe injury to an airline pilot who has had a small stroke. The horse power of the jet is still there, just like a person who might have a frontal lobe injury and still have a relatively intact memory and ability to do math and reading comprehension. However, the pilot (the frontal lobe) because of his injury is less able to control and finally maneuver the jet and difficulties will ultimately ensue. In much the same way, those with frontal lobe injury tend to suffer:
Disinhibition - which means that they lack the screening device that keeps them from saying what's on their mind. If they think, it they say it, and we can imagine the problems that would cause socially and at work. Persons with disinhibition cannot hold down a job and are often unable to keep a marriage together either.
Multitasking becomes almost impossible - The frontal lobe allows us to juggle and prioritize things and that is extraordinarily difficult with this type of injury.
Initiating activity becomes more difficult - People with this injury often are described as being "in idle" until they are prompted to do what used to be normal activities for them.
Social awkwardness is almost universally noted - This is because the frontal lobe is the part of the brain that deciphers the many nuance complexities of interacting with people. We take it for granted, but there are many, many clues visual, auditory and positional that have to be integrated into dealing with people in almost any way. People with frontal lobe injury are often described as "off rhythm" of "a step behind" in conversations. Without knowing the exact emotional temperature of the person you are speaking to, it is more likely that mistakes and problems will arise.
People with frontal lobe injuries fill our prisons, homeless shelters, and mental institutions. This is because the ability to resist criminal activity or other immoral acts is diminished with frontal lobe injury. Remember - with this injury you are more animal and less human. Because of this I describe frontal lobe injuries in many cases as "the amputation of the soul."
A frontal lobe injury will also diminish the cognitive reserve of a victim, making them more likely to face old age dementia at an earlier age and be more vulnerable to Alzheimer's as they age (see article on cognitive reserve).
Cognitive retraining and keeping the brain as busy as possible with the most complex things possible will help it rewire (neuroplasticity) after an injury or accident. We know that the human frontal lobe is not fully developed until age 21 or 22 and it is the last thing to mature. Thus, many people who have had a frontal lobe injury are described as "more immature" than they were before the injury. Sadly, many families are left caring for an adult who has the judgment of a 14 year-old and acts accordingly. It is a devastating thing to be around and to endure.