BEHAVIORAL DISORDERS   [ back to Brain Injury 101 ]
These are problem behaviors which arise as a consequence of the TBI, especially with frontal lobe damage. Examples are apathy, loss of motivation, irritability, anger, aggressiveness, inappropriate laughing or crying, socially inappropriate speech which is obnoxious or offensive, loss of ability to keep up in normal conversation and loss of ability to take charge of a situation in a responsible and reliable way (e.g. to watch the children when the non-injured spouse goes shopping or to answer calls and take down information correctly at the office when a co-worker leaves). These kinds of problem behaviors can and do erode relationships to the point where the non-injured spouse will seek marital separation or dissolution or the employer will terminate the employment. These behaviors are often tolerated and excused early on after the TBI patient comes home or returns to work, but as these behaviors continue over time and disrupt the orderly flow of business in the home or workplace, they trigger greater annoyance and intolerance in others. To prevent irrevocable breakdown in important relationships, it is important to acknowledge these behaviors and get the patient into rehabilitation where a combination of counseling, education, drug therapy,  behavioral modification and group therapy can be employed to improve the behavioral picture and avoid a bad social or vocational outcome.

In assessing neuro-behavioral disorders following a TBI the focus is generally on the inability of the brain injured patient to monitor his own behavior either through the eyes of others or from an objective standpoint of proper behavior in a given social situation or "script." Interestingly, recent research by neurologists at the University of Iowa College of Medicine and Salk Institute proves that a person with traumatic damage to their right parietal lobe will lose his ability to accurately sense the emotions that other people are feeling from seeing their facial expressions. See Journal of Neuroscience 4/1/2000 20(7):2683-2690. The lesion impairs his ability to generate an internal "somato-sensory representation" of how he would feel if he wore the same facial expression displayed by the other. Not being able to process the emotional cue given off by the facial expressions of others, the person with this type of brain injury cannot respond appropriately except by chance. Socially appropriate behavior not only requires an ability to monitor one's own behavior from an objective point of view and control one's own impulses, but the capacity to accurately perceive what other people are feeling from clues such as their facial expression, tone of voice, etc.

Any or all of these faculties can be impaired by a TBI, depending on where the damage occurs. Damage to the dorso-lateral portion of the frontal lobes is associated with apathy and loss of drives. Damage to the orbito-frontal area of the frontal lobes (located at the bottom of the frontal lobes towards the mid-line) is associated with inappropriate verbal and physical outbursts of anger. People with this sort of damage can be identified through testing their sense of smell, since they generally have anosmia (lost sense of smell) due to damage to their olfactory nerve bundles attached to the bottom of their frontal lobes. A TBI which produces diffuse brain damage may lower serotonin output. Low serotonin levels are associated with inability to handle frustration or delay, anger, violence, homicide and suicide. Whereas a hemmorhagic contusion to the frontal lobes will be readily visible on CT, and will offer up a ready explanation for changed behavior, serotonin depletion from diffuse brain injury will not show up on standard neuro-imaging. More esoteric techniques like MRI spectroscopy must be used. Recent research confirms that stress evokes a response from cells in the dorsal raphe nucleus of the brain stem which secrete serotonin. J. Neuroscience 10/15/00 20(20):7728-7736. Adequate levels of serotonin enable a stressed person or animal to handle the situation. Inadequate serotonin secretion or delivery following stress will lead to the opposite, i.e. frustration, anger and rage.