150 Chapter 8
Retrograde and Anterograde Amnesia
As noted earlier, retrograde amnesia is loss of memory before the traumatic brain injury. This
type of amnesia can be caused by organic and psychological factors. Many patients cannot remem-
ber the event that caused the brain damage.
The organic factors causing amnesia about the causative incident involve changes in brain
chemistry. An impor tant brain structure for memory is the hippocampus. Injury of this struc-
ture, and of other parts of the brain, can produce a change in brain chemistry leading to loss
of memory of the incident. The psychological factor associated with post-traumatic amnesia for
the incident is repression (Tanner, 2003a, 2012), a protective defense mechanism used to block
memories of distressing or threatening events. Repression occurs subconsciously, outside of the
person’s awareness.
Anterograde amnesia affects the acquisition of new memories. It can be minimal, involving
only memory for events immediately after the accident, or it can be extensive, destroying the
ability to learn new information. Although both retrograde and anterograde amnesia can be
significant in the patient’s recovery, the ability to lay down new memories is essential to reha-
bilitation. It is necessary to profit from experience, and thus benefit from teaching, training,
and counseling.
Both short- term and long- term pro cesses are involved in learning and acquiring new memo-
ries. Short- term memory includes attending to and remembering information while rehearsing it.
Remembering a telephone number is a good example. The average person can remember seven
numbers, with a range from five to nine. In the United States, local telephone numbers are seven
digits in length. After the number is looked up in the telephone book, it can be remembered as
long as the person rehearses it, either aloud or in the mind. However, if the person is interrupted
during the rehearsal, the number is lost and must be looked up again. In long- term memory, the
number is remembered even when it is not rehearsed. Numbers are associated with other informa-
tion in the person’s mind. With long- term storage, new information is available for purposeful or
incidental recall.
Metacognition, Mental Executive Functioning, and
Traumatic Brain Injury
Executive functioning is the mental ability to execute, regulate, plan, and monitor be hav iors
and actions. The idea comes from business, where the top executive of a corporation is respon-
sible for running it and monitoring its affairs. Executive functioning is part of metacognition:
thinking about thinking. Metacognition is the monitoring of cognitive pro cesses (Gillis, 1996).
It encompasses knowing how and when to attend to information and when and what to remem-
ber. Metacognition is knowing when prob lems exist and strategies for solving them. It is a more
encompassing concept than executive functioning and accounts for the be hav ior prob lems seen in
persons with traumatic brain injury.
Traumatic Brain Injury and Behavioral Problems
The be hav ior of many patients changes during recovery from traumatic brain injury. Early on,
they may be unresponsive; gradually, they become more responsive to persons and things. They
may also become withdrawn and distant or agitated and aggressive. Many of these changes in
be hav ior are seen as temporary and necessary stages in recovery.
Some patients with traumatic brain injury become socially disinhibited, no longer appreci-
ating and instead violating societal norms. Many of these violations involve sexual be hav iors.
Sometimes patients lose their modesty and enter public places partially or completely unclothed.
Sexual drives may be misdirected and inappropriate. Patients may become hypersexual and appear