Showing papers in "Aging Neuropsychology and Cognition in 1997"

The betula prospective cohort study: Memory, health, and aging

Abstract: The objective of this article is to present an overview of a prospective cohort study involving a total of 3,000 subjects whose ages were 35, 40, 45, 50, 55, 60, 65, 70, 75, and 80 years when first tested. the design of the study includes three waves of data collection. the first of these waves was conducted in 1988-1990, the second in 1993-1995, and the third will be conducted in 1998-2000. One sample of 1,000 subjects in these age cohorts underwent testing in 1988-1990 (100 subjects per cohort). This sample and two additional samples were tested in 1993-1995 and will be tested again in 1998-2000. Subjects take part in extensive health and memory examinations, and interviews about social factors. the memory testing covers a wide range of memory functions. the chief objectives of the study are to (a) examine the development of health and memory in adulthood and old age; (b) determine early preclinical signs of dementia; (c) determine risk factors for dementia; and (d) assess premorbid memory func...

Effect of age on forward and backward digit spans

Abstract: A number of studies has suggested that aging is characterized by a decline in the central executive while the automatic processes (in particular operations by the phonological loop) remain intact According to interpretation, age differences should be minimal in verbal forward digit span while they should be more important in backward verbal digit span A sample of 1,000 subjects with ages ranging from 16 years to 79 years was used to test this hypothesis the results show no significant effect of age on the difference between digit span forward and backward the theoretical implications of these results are discussed

Prospective memory and aging: The effects of working memory and prospective memory task load

Abstract: A person's level of engagement in other actions may influence whether a prospective action is correctly performed. This study used a computerized prospective memory task in which participants remembered to perform an action when a specified background pattern appeared while they simultaneously performed a verbal working memory task. Amount of engagement in the working memory task was manipulated by increasing the number of words to be recalled. Prospective memory load was manipulated by varying the number of prospective targets. Older adults performed more poorly than younger adults on the prospective memory task under higher working memory load and also higher prospective load. Participants with lower working memory load performed better on the prospective task, regardless of age. There were no significant age differences in the absolute accuracy of performance postdictions (post experiment performance awareness). Age differences were also found with a second prospective memory task in which par...

Remembering to remember in adulthood: A population-based study on aging and prospective memory

Abstract: Age-related differences in prospective memory were investigated in a population-based sample of healthy adults aged 35 to 80 years (N = 1,000). Participants were screened on a variety of demographic, psychological, and biological variables, including (a) subjective and objective assessment of health status; (b) information about socioeconomic background; and (c) extensive examination of basic cognitive functions. the prospective memory task was incidental and relatively realistic in the sense that the participants were asked to remind the experimenter to sign a paper after a 2-hour test session. Results indicated an overall deterioration of prospective memory performance across age. Furthermore, age-related differences in prospective memory were observed even when differences in the selected background variables were taken into consideration.

Age differences in inhibition: Possible causes and consequences

Abstract: The relations among age, inhibition, perceptual speed, susceptibility to interference, and working memory were examined in a sample of 301 adults age 20 to 90. Younger adults were found to have more efficient inhibitory mechanisms than were older adults. Significant inhibition, however, was found in all age groups, including the older age group. Older adults were also found to be more susceptible to interference from irrelevant information. There was a small negative relation between interference and inhibition, suggesting that participants with the most efficient inhibitory functioning may be the least susceptible to interference. Perceptual speed, an index of processing efficiency, was found to mediate nearly all of the age-related variance in inhibition and interference. Interference, but not inhibition, was found to mediate some of the age-related variance in working memory.

Age differences in feature and conjunction search: Implications for theories of visual search and generalized slowing

Abstract: Reaction times (RTs), saccadic eye movements, and fixation durations were measured while older and younger observers searched visual displays for targets defined by a single feature, luminance contrast or orientation, as well as the conjunction of these two features. Target eccentricity was varied between approximately 4 and 14 deg. Age deficits generally increased in the more difficult conditions. the RT data indicated that age deficits were greatest for conjunction search and on target absent trials. the saccade data showed that on target present trials, age deficits were larger for more eccentric targets, especially in conjunction search. Fixation durations were related by a power function to the number of saccades made prior to a correct response. Whereas the exponent of these power functions was constnat across search condition and age group, the coefficient was larger for older adults. Thus at a fixed number of saccades, when old and young were presumably searching groups of equal size, the...

The neural noise hypothesis: Evidence from processing speed in adults with multiple sclerosis

Abstract: On measures of speeded performance, adults with multiple sclerosis (MS) typically respond more slowly than do adults without MS. A review of 12 published studies yielded 38 pairs of response times (RTs) in which each pair consisted of a mean RT for a sample of persons with MS for an experimental condition and the corresponding mean RT for a sample of persons without MS. the primary result was that, across the 38 conditions, RTs for individuals with MS increased linearly as a function of RTs for persons without MS. Because MS involves demyelination of the axons in the central nervous system (CNS), it is suggested that this result provides support for the neural noise hypothesis of cognitive aging.

How cognitive is psychomotor slowing in depression? evidence from a meta-analysis

Abstract: The current meta-analysis explores the hypothesis that many of the apparently specific deficits that depressed subjects show on speeded cognitive tasks are actually the result of general (i.e., task-independent) slowing. Results of three analyses provided strong support for this hypothesis. the reaction times (RTs) of the depressed groups were consistently slower than those of the control groups. Moreover, the degree of cognitive slowing was approximately the same regardless of the task or condition. Regression analyses revealed a proportional relation between the RTs of the two depressed and control groups, suggesting that depression slows sensory/motor and cognitive processes to approximately the same degree. the regression-based approach used in the present analyses has implications for the study of other neurological disorders and also may have important applications in the assessment of both general and specific cognitive deficits in individual patients.

Adult age differences in strategic and dynamic components of focusing visual attention.

Abstract: Changes in the width of a focally attended area were assessed by analysis of changes in reaction time associated with response-incompatible nontarget letters (flankers). In two experiments, the focus of attention widened as an increasing function of stimulus onset asynchrony (SOA). In contrast to the predictions of generalized slowing and inhibition-deficit models, this dynamic change in attention was comparable for young and older adults in both experiments. Evidence accumulation outside the focus of attention was greater for young adults than for older adults when target location varied (Experiment 2). This latter effect, however, was strategic (i.e., independent of SOA). Analyses of the task complexity functions (Brinley plots) indicated a greater contribution of generalized slowing when target location was constant (Experiment 1) than when location varied (Experiment 2).

Effects of aging on voluntary and involuntary shifts of attention.

Abstract: This experiment examined adult age differences in the speed and accuracy of voluntary and involuntary shifts of visual attention. Younger and older adults performed two spatial cuing tasks using central cues and abrupt onset peripheral cues presented at stimulus onset asynchronies (SOAs) of 100, 150, 200, 250, and 300 ms. Analyses of the magnitudes of cuing effects revealed a similar time course for younger and older adults in the central cue condition, but not in the peripheral condition. Analyses of the Brinley plot for central cues across cue validity conditions indicated that as much as 93% of the variance could be attributed to age-related general slowing rather than to differential aging of a specific visual orienting mechanism.

Proper name retrieval in old age: Converging evidence against disproportionate impairment

Abstract: In this article, the task of separating specific from general effects of normal aging on cognition is illustrated by considering the retrieval of proper names as a possible case of exceptional or disproportionate age-related impairment. First, existing evidence both for and against disproportionate impairment is reviewed from several sources, including self-rated questionnaires, diary and laboratory studies of memory failures, and the speeded naming of objects versus people. Some new regression analyses of naming responses are then presented; they demonstrate that the effect of age on proper name retrieval can be removed by taking into account the effect of age on other processes not involving proper name retrieval. Finally, data from face and voice identification tasks are analyzed in terms of conditional probabilities which reveal that the effect of age on the final stage of name retrieval is no greater than the effect of age on the earlier stages of recognition and semantic information retriev...

Group differences in suppression skill

Abstract: It is proposed that there are group differences in suppression skill, and one such grouping is the distinction between more versus less skilled university-aged comprehenders. Experiments supporting this proposal and demonstrating that university-aged adults differ in their ability to suppress irrelevant, inappropriate, potentially interfering information are reviewed. Many of these experiments have been replicated with other groups, which also hypothetically differ in their ability to suppress inappropriate information. Two new sets of experiments are reviewed. In one, the prediction that less skilled comprehenders - because they are less skilled at suppression - should be better at comprehending puns is evaluated. In the other, the prediction that less skilled comprehenders - because they are less skilled at suppression - are better able to shift to a different meaning of a homonym is evaluated. Both sets of data are evaluated with respect to a general slowing explanation and scaling artifacts.

Influences of clustering and switching on the verbal fluency performance of patients with alzheimer's disease.

Abstract: Several lines of evidence suggest that in Alzheimer's disease (AD) there is a progressive degradation of the hierarchical organization of semantic memory. to evaluate this hypothesis, clustering and switching on phonemic and semantic fluency tasks were studied. For elderly controls, both clustering and switching were correlated with the numbers of correct words generated on both fluency tests, but the contribution of clustering was greater on the semantic task. Patients with AD generated fewer correct words and made fewer switches than controls on both fluency tests. the average size of their semantic clusters was smaller and the contribution of clustering to word generation was less than for controls. Severity of dementia was correlated with the numbers of correct words and switches, but not with cluster size. These results are consistent with various hypotheses which maintain that the structure of semantic memory in AD is degraded but provide no evidence that this process is progressive. Instead, progressive worsening of verbal fluency in AD seems to be more strongly associated with the deterioration of mechanisms that govern initiation of search for appropriate subcategories.

Effects of working memory capacity on understanding rate-altered speech

Abstract: Age-related declines in language processing have been attributed in part to generalized cognitive slowing. Because of this slowing, it has been suggested that older adults' sentence comprehension might be facilitated by reducing the rate at which sentences are spoken. Research, however, has failed to reliably show that speaking slowly enhances comprehension. the present study explores the hypothesis that declines in working memory (WM) would actually counteract any benefits derived from a reduction in speech rate. That is, at a slower than normal speech rate, more demands are placed on WM since information must be retained over a longer duration. the comprehension of normal and slow speech was examined for three Alzheimer's subjects, each presenting a unique profile of WM capacity. Results suggest that the effect of speech rate on comprehension is determined by the extent of WM capacity: A slow speech rate was beneficial only for the subject with the most preserved WM; speech rate did not affect ...

Working memory and aging: Deficit or strategy differences?

Abstract: Thirty young and 30 older subjects were administered a reading comprehension test and a working memory test involving processing of acceptable and incongruous sentences with an increasing mnemonic preload. the complexity of incongruous sentences was assumed to solicit the processing component of working memory, whereas the size of the mnemonic preload was assumed to solicit its storage component. Results suggested not only reduced working memory capacity in older subjects, but also a change in their strategies relative to both the sentence processing/word recall and the speed/accuracy trade-offs: Older subjects favored sentence processing to the detriment of word recall, and a subset of them favored accuracy to the detriment of speed when the memory load was heavy. This change of strategy was reflected by the pattern of correlations between working memory measures and reading comprehension scores, in that the best comprehension scores were reached by the fastest young subjects, but by the most ac...

Differential effects of aging on explicit and implicit memory

Abstract: In the present study, five consecutive age groups ranging from the 20s to the 60s were compared on a range of explicit and implicit memory tests which were modelled on the clinical tasks used to assess amnesia. With respect to explicit memory, the ability to recall verbal or visual material was seen to decline steadily with increasing age at immediate and delayed testing; there were, however, no consistent age differences regarding performance on recognition tasks. Perceptual skill acquisition within the context of a mirror reading task was unaffected by age, while word stem completion priming tended to decline across the age groups. Factor analysis revealed three factors: verbal explicit memory, visual memory (comprising visual recall and stem completion priming), and skill acquisition. the present findings indicate dissociable effects of normal aging on explicit and implicit memory, and thereby some degree of qualitative resemblance to human amnesia.

Varying patterns of verbal recall, recognition, and response bias with progression of Alzheimer's disease

Abstract: Aspects of performance on verbal list learning tasks, such as recall, recognition, and response bias, may vary with severity in Alzheimer's disease (AD). We administered a 10-item, single-category word list learning test using selective reminding procedures to 188 patients with probable AD and 36 healthy normal controls with equivalent age and education. We analyzed the total number of words recalled as well as discrimination and response bias indexes derived from signal detection theory. Recall and discrimination were impaired in patients with probable AD compared to controls, and recall scores were more sensitive to dementia severity than discrimination. While many AD patients showed a liberal response bias, their response bias varied considerably within patient groups and did not correlate with disease severity.

Memory improvement tapes: How effective for elderly adults?

Abstract: The effectiveness of two commercially available audiocassette memory improvement programs was evaluated in a sample of 32 healthy, community-living elderly adults. Participants were given a set of either Syber Vision's Neuropsychology of Memory Power tapes (Bornstein, 1989) or Nightingale-Conant's Mega Memory tapes (Trudeau, 1992), and a portable cassette player, and instructed to complete the programs within 10 weeks. All participants received a comprehensive battery of memory tests prior to and immediately following the memory improvement programs. Participants completing the memory improvement programs showed no greater gains in memory test performance than no-treatment control participants, but did report greater confidence in their memory abilities. Participants completing the Mega Memory program thought they were less likely to develop Alzheimer's disease after having completed it compared with participants in the other two conditions. Participants reported finding both tape programs accept...

Effects of age and education on neuropsychological test performance: A comparison of normal versus cognitively impaired geriatric medical patients

Abstract: The effects of age and education on neuropsychological test performance were examined in samples of cognitively intact (n = 51) and demented (n = 99) geriatric inpatients. Using Fisher's r to z procedure, no between sample differences for correlations were found, except for the relationship between Wechsler Memory Scale-Revised Logical Memory II performance and age (z = 1.68; p <. 05). These results are discrepant with those of previous studies that question the validity of demographically based score corrections for younger patients with neurological disease (e.g., Reitan & Wolfson, 1995). the authors advocate the consideration of demographic influences on neuropsychological test performance, particularly when evaluating older, less educated persons.

Unawareness of social interaction and emotional control deficits in alzheimer's disease

Abstract: The purpose of this study was to examine unawareness of deficit in Alzheimer's disease (AD) in a previously unexplored functional domain: social interaction and emotional control competency. Impairment of awareness was measured by calculating the degree to which patients and their caregivers disagreed on ratings of patient functioning. to assess potential underlying mechanisms or associated features of social/emotional unawareness, a regression equation examining disease and demographic correlates was created. In addition, to provide a basis of comparison for the social/emotional domain, unawareness of deficit was also assessed in two previously examined domains of functioning (i.e., cognitive and self-care competency). Results revealed that, as compared to caregivers, AD-diagnosed patients overestimated their social/emotional competency but to a lesser extent than they overestimated cognitive and self-care competencies. Regression analysis suggested that impaired awareness of social interaction ...

Age, context, and spatial memory: A neuropsychological approach

Abstract: The hypothesis that a reduction in age differences in spatial location memory in the presence of distinctive cues reflects a decreased dependence on a hippocampally based memory system was tested in three experiments. In Experiments 1 and 2 the presence of distinctive cues did not reduce age differences in spatial location memory nor did these cues eliminate the significant relation between spatial location memory and a measure of hippocampal function. Distinctive cues did, however, place additional demands on processing resources and spatial visualization abilities. In Experiment 3 the relevance of prior knowledge was manipulated. With irrelevant prior knowledge there was a strong unique association between the hippocampal measure and outcome measure. With relevant prior knowledge there was no such association. the implications of these findings for understanding the role of the hippocampus in age-related decline in memory for locations are discussed.

Pictorial rehearsal effects in younger and older adults

Abstract: In three studies, we examined pictorial rehearsal effects in younger and older adults. Concrete and abstract line drawings that varied in the amount of pictorial detail were presented for study under different presentation conditions. In the pictorial rehearsal condition, each picture was followed by a blank rehearsal interval where the picture was no longer presented. In all three experiments, the poststimulus interval enhanced picture recognition for both age groups, relative to a control condition where no rehearsal interval occurred. These findings suggest that older adults, like younger adults, form and maintain visual images across a blank rehearsal interval. Implications of these findings for current views on imaginal processes in older adults are discussed.