In the Korsakoff amnesic syndrome, newly presented material appears to be correctly registered but cannot be retained for more than a few minutes (anterograde amnesia, or failure of learning). In this syndrome, there is always an associated defect in the recall and reproduction of memories that had been formed several days, weeks, or even years before the onset of the illness (retrograde amnesia). The fabrication of stories, called confabulation, constitutes a third feature of the syndrome but is neither specific nor invariably present. Intact retention with failure of recall (retrograde amnesia without anterograde amnesia) when it is severe and extends to all events of past life and even personal identity, is usually a manifestation of hysteria or malingering. Certain other characteristic defects occur in almost all memory disorders, for example, the relative retention of older memories in preference to newer ones (Ribot’s rule). Chapter 19 discusses this subject more fully.
Disturbances of Thinking
Thinking, the highest order of intellectual activity, remains the most elusive of all mental operations. If by thinking one means the selective ordering of symbols for learning, organizing information, and problem solving, as well as the capacity to reason and form sound judgments, then the working units of this type of mental activity are words and numbers. The substitution of words and numbers for the objects for which they stand (symbolization) is a fundamental part of the process. These symbols are formed into ideas or concepts, and the arrangement of new and remembered ideas into certain orders or relationships constitutes an intricate part of thought, presently beyond the scope of analysis. Reference is made further on to Luria’s analysis of the steps involved in problem solving in connection with frontal lobe function, but actually, as he points out, the whole cerebrum is implicated in all forms of thinking. One may examine thinking in terms of its speed and efficiency, ideational content, coherence and logical relationships of ideas, and the quantity and quality of associations to a given idea.
Aphasic disturbances are not prominent in global confusional and delirious states, but Geschwind discussed misnaming as an important feature among the “nonaphasic disorders of speech” in these conditions. Spontaneous speech is normal, but there may be inaccuracies in repetition that are most likely the result of inattention rather than a focal cerebral lesion.
Disorders of thinking are quite prominent in the global confusional state, in mania, dementia, and schizophrenia. In confusional states of all types, the organization of thought processes is disrupted, with fragmentation, repetition, and perseveration; this is spoken of as an “incoherence of thinking.” Derangements of thinking may also take the form of a flight of ideas; patients move too facilely from one idea to another, and their associations are numerous, and loosely linked. This is a common feature of hypomanic and manic states, and of some schizophrenic psychoses. The opposite condition, poverty of ideas, is characteristic both of depressive illnesses, in which it is combined with gloomy thoughts, of schizophrenia, and of dementing diseases, in which it is part of a reduction of all inner psychic intellectual activity. This overall reduction in thought and action is the most prominent feature of diseases that damage the frontal lobes.
A related condition of slowed thought, or bradyphrenia, is comparable to the bradykinesia of extrapyramidal disorders. The two often coexist and the patient, for example with Parkinson disease, can articulate that thinking is so slow as to be virtually blocked. The content of thought is not much altered, but it may be rendered almost useless when slowed to this degree. The outward manifestation of bradyphrenia is what one would expect, a delay in response and slowness in gathering one’s thoughts to express ideas.