2 results
20 - Preserved cognitive skills in neurodegenerative disease
- from PART III - Clinical perspectives
- Edited by Alexander I. Tröster, Kansas University Medical Center
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- Book:
- Memory in Neurodegenerative Disease
- Published online:
- 23 November 2009
- Print publication:
- 29 October 1998, pp 338-348
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- Chapter
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Summary
INTRODUCTION
Progressive dementing diseases, regardless of their etiology, are associated with a relentless loss of cognitive capability in many domains, which in turn is associated with demonstrable and varied neuropathological changes, most of which are irreversible. From this perspective, it is not surprising that extensive research effort has been devoted to the careful description of the various cognitive and neuropathological changes that occur in both Alzheimer's disease and in vascular dementia. Because the changes that occur in the brain with these diseases are cumulative and eventually result in marked tissue loss, current conceptions about the nature of cognitive deficits have implicitly or explicitly assumed that these deficits arise because the necessary information to perform the cognitive functions is simply ‘gone’, on account of the neural substrate being either absent or hopelessly ‘scrambled'.
Against this background, demonstrations that some demented patients retain the ability to perform some complicated activities quite well even though they apparently can no longer perform simpler functions competently pose fascinating theoretical questions, which in turn may have important practical implications. In this chapter we review the literature on preserved cognitive skills in dementia. As a prelude, it is desirable to consider what is known about the status of everyday cognitive skills in normal aging and in amnesia. Finally, the literature on savants is also reviewed briefly because savants, like some demented elderly patients, also exhibit exceptional cognitive abilities against a background of globally impaired intellectual functioning.
NORMAL AGING
Age-related declines in performance have been carefully documented on tests of sensory acuity, psychomotor speed, recent memory, attention, visuospatial and visuoperceptual abilities and forming novel concepts (Flicker et al. 1986; Salthouse 1989, 1990).
10 - Remote memory in neurodegenerative disease
- from PART II - Cognitive perspectives
- Edited by Alexander I. Tröster, Kansas University Medical Center
-
- Book:
- Memory in Neurodegenerative Disease
- Published online:
- 23 November 2009
- Print publication:
- 29 October 1998, pp 184-196
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- Chapter
- Export citation
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Summary
INTRODUCTION
Memory is the cognitive domain most vulnerable to brain injury. Accordingly, the research literature on memory impairment in brain damage is vast, but most of it concerns deficits that occur after the time of brain injury (or the presumed onset of degenerative disease), that is, anterograde amnesia. Much less is known about the ability of patients to recollect information acquired prior to the onset of disease, yet the practical consequences of marked impairments in remote memory (i.e. retrograde amnesia) are likely to be more serious for an elderly person with dementia than are equally severe anterograde memory deficits. Specifically, a patient's complete failure to remember any of the items on a grocery list does not meaningfully increase the caregiver's burden, because the patient would not be expected to do the shopping anyway. By contrast, if the dementia patient repeatedly wanders away from home and cannot remember how to return (a failure of remote visuospatial memory), the burden on the caregiver is great and institutionalization of the patient is a likely consequence.
One reason why the study of remote memory has languished is because of theoretical and methodological problems. This chapter reviews the applicability of the theoretical distinction between episodic and semantic memory to remote memory and then the methods used to study remote memory. After highlighting limitations of these methods, the chapter summarizes the findings of studies of remote memory in normal aging, amnesia and neurodegenerative diseases.