Something was wrong with the 40-year old schoolteacher from Virginia….He had begun collecting child pornography, soliciting prostitutes, and making sexual advances to his stepdaughter. Eventually his wife found out and he was ordered either to complete a Sexaholics Anonymous program or face jail time. Despite the threat of jail time, he failed the program because he could not stop himself from asking the other members for sexual favors. The night before he was scheduled for sentencing, the man went to a hospital and complained of severe headaches. Doctors found a large brain tumor displacing his orbitofrontal lobe. After the tumor was removed, the deviant urges subsided and he was allowed to return home.
There are two interesting implications of this story. Either some urges were being dis-inhibited, or they were being created, or both, by the tumor. Perhaps an inactivation of the frontal lobes was affecting the willpower to control the urges.
For a lawyer, using the insanity defense on a person like this is difficult, first of all because the person still knows what he is doing is wrong, and secondly because he is in touch with reality.
Frontal lobe damage can be caused by car accidents, where there can be sudden forces of acceleration and deceleration exerted on the skull. Sometimes the damage is subtle, so the victims don’t know they have been affected. Accident victims may notice their behavior has changed, but may blame it on an inability to cope with the accident.
Schizophrenics often exhibit abnormal frontal lobe functioning.
(I once read that even snowboarders can get this type of damage. I’ve probably lost all my frontal lobes due to my bumpy mountain biking, but the article I read featured a snowboarder registering blank areas on his brain MRI.)
Children have less developed frontal lobes than adults, which may suggests that adults develop more self-control. However, children don’t have the “marked apathy, tactlessness, impulsivity, irritability, and inability to empathize” that often happens with frontal lobe damage.
It is true also that damage to the frontal lobes is a significant cause of violent and aggressive behavior and negative personality changes.
But before we jump to the conclusion that evil is just a result of an impaired frontal lobe, we should pay attention to Adrian Raine’s study where he applied PET scans to murderers and found they fell into 2 groups. One group indeed had impaired frontal lobe functioning – these were the impulsive emotionally charged killers. The other group had controlled purposeful aggression to achieve a desired goal. That group had perfectly functioning frontal lobes. And the latter group is one we would associate more with our stereotype of evil. People who can’t help themselves don’t fit our definition of evil, though they cause evil. I suppose you might argue that somewhere in the deep recesses of the limbic system of the types that know exactly what they are doing there is a miswired circuit. But nothing like that has been shown to be true, as of 2011.
Interestingly, there are drugs that mitigate frontal lobe damage, such as Ritalin, and some mood stabilizers.
Source: The Criminal Brain by Jessie Seiden (this article is on the internet)