DERANGEMENTS OF INTELLECT, BEHAVIOR, AND LANGUAGE CAUSED BY DIFFUSE AND FOCAL CEREBRAL DISEASE
Physicians, through hard clinical experience, discover the need for competence in assessing the mental faculties of their patients. They must be able to observe with objectivity the patient’s attention, memory, judgment, mood, character, and other attributes of cognition, and personality in much the same fashion as they observe the patient’s movements, gait, and reflexes. An examination of these intellectual and affective functions permits the physician to reach conclusions regarding a patient’s mental status and its relationship to their illness. Without such an assessment, even if informal, there are likely to be errors in the diagnosis and treatment of neurologic, general medical, and psychiatric disease.
The content of this section will be more clearly understood if a few of the introductory remarks to the later chapters on psychiatric diseases are anticipated here. The main thesis of the neurologist is that mental and physical functions of the nervous system are two parallel aspects of the same neural processes. Mind and behavior both have their roots in the self-regulating, goal-seeking activities of the organism, the same ones that provide an impulse to all forms of mammalian life. But the complexity of the human brain permits the solving of difficult problems, the capacity for remembering past experiences and casting them in a symbolic language that can be written and read, and the planning for events that have yet to take place. The constant but sometimes meandering internal verbal experience of this ideation during waking was named “stream of thought” by William James. Somehow, there emerges from these complex cerebral functions, a continuous awareness of one’s self and the operation of one’s psychic processes. It is this inner consciousness that might be called mind. Whether this is an emergent property of various mental functions or simply their representation as an idea in the mind cannot be answered, but any wide separation of the mental from the observable behavioral aspects of cerebral function is probably illusory. The physician is persuaded of the truth of this view through daily clinical experience, in which every possible aberration of behavior and intellect appears at some time or other as an expression of cerebral disease. However, whether the workings of the mind, as defined above, can be fully understood by a complete knowledge of the workings of the brain, has been a philosophical conundrum since antiquity. In other words, the mind seems to have its own vague set of rules that have been taken up by the field of psychology. Nevertheless, in many brain diseases, particularly the forms of confusion addressed in the first chapter in this section on confusional states, one witnesses parallel disorders of the patient’s behavior and a dissolution or distortion of the introspective awareness of his own mental capacities.
The reader will find that Chaps. 19 and 20 are concerned with common disturbances of sensorium and cognition, which ...