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Neuropsychological correlates of health risk in the elderly
601
TENNET I
Perhaps the most consistent observation in the psychology of aging is an age-related decrease in speed of performance of cognitive tasks. Despite the ubiquity of the age-related slowing phenomenon, attempts to identify its mechanisms have met with little success. To overcome this limitation, we propose a Computational Approach to age differences in cognition. We begin with a critique of the Generalized Slowing and Resource Reduction Hypotheses. These positions view the effects of aging on cognition as quantirative-linked to the amount, rather than the type of information processing. To assess this claim, we review chronometric and event-related potential studies that have attempted to attribute age-related slowing to decreases in the rate of central and/or peripheral processes. From this review we conclude that: (1) there is a tendency for cognitive operations to become less efficient with age; and (2) the extent of age-related slowing present in central and/or peripheral processes varies markedly between tasks. These conclusions suggest a model wherein age differences are both quantitative and qualitative-linked to specific types of information processing, attributable to relatively independent changes in the efficiency of particular cognitive modules. 24. Neuropsychological SEGALOWITZ,
Correlates
AND AYSE
UNSAL,
of Health Risk in the Elderly.
JANE DYWAN,
SIDNEY
Department of Psychology, Brock University,
J. St.
Catharines, Ontario. A battery of neuropsychological and electrophysiological measures were administered to 18 independently functioning elderly volunteers from the community and were rated on two health indices: general health and neurological risk factors. Results suggest a dissociation between frontal functions and certain posterior functions in the pattern of their decline. Health indices predicted Wisconsin Card Sort (WCS) perseverative errors, which have been associated with dysfunction of the prefrontal lobe, but not nonperseverative errors. Signal processing efficiency, as measured by P300 latency, predicted WCS nonperseverative errors and other nonfrontal lobe functions, but not perseverative errors. We argue that the P300 latency and WCS scores reflect systems which are at risk in different ways: Frontal lobe is particularly associated with and possibly the first to show sensitivity to cardiovascular risk, while general cognitive decline in the elderly is due to reduced speed of information processing. on Discourse Comprehension in Aging. HELEN J. KAHN, Laboratoire Theophile Alajouanine, Centre Hospitalier C&e-des-Neiges, Montreal, Quebec.
25. The Effect of Prior Knowledge
Linguistic changes that occur in association with advancing age have been of interest to neuropsychology because recent evidence has suggested that some types of linguistic errors seen in aphasic patients may also occur in normal older adults. This study investigated whether older adults’ referential ability in discourse comprehension could be facilitated by world knowledge. Old and young subjects read stories ranging in length and selected the antecedents for sentences which contained referent nouns and properties that were consistent, inconsistent, or neutral with respect to world knowledge. Older adults were equally accurate as the young when the pronoun referred to consistent information, but were significantly less accurate for reference to inconsistent and neutral information. There was no effect of referential distance (memory load between noun and pronoun) with age. It is argued that an age-related dissociation between semantic and episodic memory may account for these results, since it has been shown that semantic memory remains stable with age, while episodic memory may decline. For the older adult, an intact semantic system may facilitate reference for text consistent with prior knowledge, even when antecedent information is forgotten, but provides little benefit for temporally dated, episodic information.
TENNET I
Perhaps the most consistent observation in the psychology of aging is an age-related decrease in speed of performance of cognitive tasks. Despite the ubiquity of the age-related slowing phenomenon, attempts to identify its mechanisms have met with little success. To overcome this limitation, we propose a Computational Approach to age differences in cognition. We begin with a critique of the Generalized Slowing and Resource Reduction Hypotheses. These positions view the effects of aging on cognition as quantirative-linked to the amount, rather than the type of information processing. To assess this claim, we review chronometric and event-related potential studies that have attempted to attribute age-related slowing to decreases in the rate of central and/or peripheral processes. From this review we conclude that: (1) there is a tendency for cognitive operations to become less efficient with age; and (2) the extent of age-related slowing present in central and/or peripheral processes varies markedly between tasks. These conclusions suggest a model wherein age differences are both quantitative and qualitative-linked to specific types of information processing, attributable to relatively independent changes in the efficiency of particular cognitive modules. 24. Neuropsychological SEGALOWITZ,
Correlates
AND AYSE
UNSAL,
of Health Risk in the Elderly.
JANE DYWAN,
SIDNEY
Department of Psychology, Brock University,
J. St.
Catharines, Ontario. A battery of neuropsychological and electrophysiological measures were administered to 18 independently functioning elderly volunteers from the community and were rated on two health indices: general health and neurological risk factors. Results suggest a dissociation between frontal functions and certain posterior functions in the pattern of their decline. Health indices predicted Wisconsin Card Sort (WCS) perseverative errors, which have been associated with dysfunction of the prefrontal lobe, but not nonperseverative errors. Signal processing efficiency, as measured by P300 latency, predicted WCS nonperseverative errors and other nonfrontal lobe functions, but not perseverative errors. We argue that the P300 latency and WCS scores reflect systems which are at risk in different ways: Frontal lobe is particularly associated with and possibly the first to show sensitivity to cardiovascular risk, while general cognitive decline in the elderly is due to reduced speed of information processing. on Discourse Comprehension in Aging. HELEN J. KAHN, Laboratoire Theophile Alajouanine, Centre Hospitalier C&e-des-Neiges, Montreal, Quebec.
25. The Effect of Prior Knowledge
Linguistic changes that occur in association with advancing age have been of interest to neuropsychology because recent evidence has suggested that some types of linguistic errors seen in aphasic patients may also occur in normal older adults. This study investigated whether older adults’ referential ability in discourse comprehension could be facilitated by world knowledge. Old and young subjects read stories ranging in length and selected the antecedents for sentences which contained referent nouns and properties that were consistent, inconsistent, or neutral with respect to world knowledge. Older adults were equally accurate as the young when the pronoun referred to consistent information, but were significantly less accurate for reference to inconsistent and neutral information. There was no effect of referential distance (memory load between noun and pronoun) with age. It is argued that an age-related dissociation between semantic and episodic memory may account for these results, since it has been shown that semantic memory remains stable with age, while episodic memory may decline. For the older adult, an intact semantic system may facilitate reference for text consistent with prior knowledge, even when antecedent information is forgotten, but provides little benefit for temporally dated, episodic information.