Gender differences in the trajectories of late-life depressive symptomology and probable depression in the years prior to death.

BACKGROUND: Gender differences in depression are well established. Whether these differences persist into late life and in the years preceding death is less clear. There is a suggestion that there is no increased likelihood of depression in late life, but that there is an increase in depressive symptomology, particularly with proximity to death. We compared trajectories of probable depression and depressive symptomology between men and women over age and distance-to-death metrics to determine whether reports of depressive symptoms are more strongly related to age or mortality. METHODS: Participants (N = 2,852) from the Dynamic Analyses to Optimise Ageing (DYNOPTA) project had a mean age of 75 years (SD = 5.68 years) at baseline and were observed for up to 16 years prior to death. Multi-level regression models estimated change in depressive symptomology and probable depression over two time metrics, increasing age, and distance-to-death. RESULTS: Increases in depressive symptomology were reported over increasing age and in the years approaching death. Only male participants reported increased probable depression in the years preceding death. Models that utilized distance-to-death metrics better represented changes in late-life depression, although any changes in depression appear to be accounted for by co-varying physical health status. CONCLUSIONS: As death approaches, there are increases in the levels of depressive symptomology even after controlling for socio-demographic and health covariates. In line with increases in suicide rates in late life, male participants were at greater risk of reporting increases in depressive symptomology.

Comorbid chronic diseases, discordant impact on mortality in older people: a 14-year longitudinal population study.

OBJECTIVES: To determine the impact of comorbid chronic diseases on mortality in older people. DESIGN: Prospective cohort study (1992-2006). Associations between numbers of chronic diseases or mutually exclusive comorbid chronic diseases on mortality over 14 years, by Cox proportional hazards model adjusting for sociodemographic variables or Kaplan-Meier analyses, respectively. SETTING: Population based, Australia. PARTICIPANTS: 2087 randomly selected participants aged ≥65 years old, living in the community or institutions. MAIN RESULTS: Participants with 3-4 or ≥5 diseases had a 25% (95% CI 1.05 to 1.5, p=0.01) and 80% (95% CI 1.5 to 2.2, p<0.0001) increased risk of mortality, respectively, by comparison with no chronic disease, after adjusting for age, sex and residential status. When cardiovascular disease (CVD), mental health problem or diabetes were comorbid with arthritis, there was a trend towards increased survival (range 8.2-9.5 years) by comparison with CVD, mental health problem or diabetes alone (survival 5.8-6.9 years). This increase in survival with arthritis as a comorbidity was negated when CVD and mental health problems or CVD and diabetes were present in disease combinations together. CONCLUSION: Older people with ≥3 chronic diseases have increased risk of mortality, but discordant effects on survival depend on specific disease combinations. These results raise the hypothesis that patients who have an increased likelihood of opportunity for care from their physician are more likely to have comorbid diseases detected and managed.

A syndromal analysis of neuropsychological outcome following coronary artery bypass graft surgery.

BACKGROUND: Studies of neuropsychological outcome following coronary artery bypass graft surgery (CABG) have traditionally dichotomised patients as "impaired" or "unimpaired". This conceals the potential heterogeneity of deficits due to different mechanisms and sites of brain injury. OBJECTIVES: To explore neuropsychological outcome following CABG and determine to what extent it conforms to prototypic cortical and/or subcortical neurobehavioral syndromes and whether different intraoperative physiologic measures are associated with different subtypes of neuropsychological outcome. METHODS: Neuropsychological tests were administered to 85 patients before and after elective CABG and to 50 matched normal control subjects. Pre- to postoperative change scores were computed using standardised regression based norms. Change scores on selected memory measures were subjected to cluster analysis to identify qualitatively distinct subtypes of memory outcome. Emergent clusters were compared on non-memory measures, intraoperative physiologic measures, and demographic variables. RESULTS: Three subtypes of memory outcome were identified: memory spared (48% of patients), retrieval deficit (35%), and encoding/storage deficit (17%). Contrary to expectation, the subgroups were indistinguishable on measures of confrontation naming and manual dexterity and on intraoperative cardiac surgical physiologic measures and demographic variables. The encoding/storage deficit subgroup exhibited executive dysfunction. CONCLUSIONS: Heterogeneous profiles of neuropsychological dysfunction were found following CABG although they did not tightly conform to prototypic cortical and subcortical neurobehavioral syndromes. This challenges the value and appropriateness of the common practice of collapsing individual test scores to arrive at a single figure to define "impairment". Whether different subtypes of neuropsychological outcome are caused by different pathophysiologic mechanisms remains unknown.

Two-year decline in vision but not hearing is associated with memory decline in very old adults in a population-based sample.

BACKGROUND: Recent cross-sectional research in cognitive aging has demonstrated a robust association between visual acuity, auditory thresholds and cognitive performance in old age. However, the nature of the association is still unclear, particularly with respect to whether sensory and cognitive function are causally related. OBJECTIVE: This study aimed to determine whether marked declines in performance on screening measures of either visual acuity or auditory thresholds have an effect on cognitive decline over 2 years. METHODS: The sample from the Australian Longitudinal Study of Ageing (n = 2,087) were assessed in 1992 and 1994 on measures of sensory and cognitive function as part of a larger clinical assessment. A quasi-experimental design involving comparison of extreme groups using repeated measures MANCOVA with age as a covariate was used. RESULTS: Group performance on measures of hearing, memory, verbal ability and processing speed declined significantly. Decline in visual acuity had a significant effect on memory decline, but not on decline in verbal ability or processing speed. Decline in hearing was not associated with decline in any cognitive domain. CONCLUSION: The common association between visual acuity, auditory thresholds and cognitive function observed in cross-sectional studies appears to be disassociated in longitudinal studies.

Demographic, health, cognitive, and sensory variables as predictors of mortality in very old adults.

Cognitive and sensorimotor predictors of mortality were examined in the Australian Longitudinal Study of Ageing, controlling for demographic and health variables. A stratified random sample of 1,947 males and females aged 70 and older were interviewed, and 1,500 were assessed on measures of health, memory. verbal ability, processing speed, vision, hearing, and grip strength in 1992 and 1994. Analyses of incident rate ratios for mortality over 4- and 6-year periods were conducted using Cox hierarchical regression analyses. Results showed that poor performance on nearly all cognitive variables was associated with mortality, but many of these effects were explained by measures of self-rated health and disease. Significant decline in hearing and cognitive performance also predicted mortality as did incomplete data at Wave 1. Results suggest that poor cognitive performance and cognitive decline in very old adults reflect both biological aging and disease processes.

A reevaluation of the common factor theory of shared variance among age, sensory function, and cognitive function in older adults.

The common cause hypothesis of the relationship among age, sensory measures, and cognitive measures in very old adults was reevaluated. Both sensory function and processing speed were evaluated as mediators of the relationship between age and cognitive function. Cognitive function was a latent variable that comprised 3 factors including memory, speed, and verbal ability. The sample was population based and comprised very old adults (n = 894; mean age = 77.7, SD = 5.6 years) from the Australian Longitudinal Study of Ageing. The results showed that there was common variance in the cognitive factor shared by age, speed, vision, and hearing but that specific effects of age on cognition remained. Furthermore, speed did not fully mediate the effect of age or sensory function on cognition. Some age differences in cognitive performance are not explained by the same processes that explain age differences in sensory function and processing speed.

Adult age differences in self-ordered pointing task performance: contributions from working memory, executive function and speed of information processing.

This study investigated adult age differences in, and predictors of, the performance of a test of executive function, the Self-Ordered Pointing Task (SOPT; Petrides & Milner, 1982). Performance on the SOPT is thought to rely on high level working memory processes, therefore, measures reflecting the common operationalization of working memory, along with measures of executive function and speed of information processing, were investigated as predictors of SOPT performance. Younger (aged 17-48 years) and older (aged 65-88 years) adults completed a 16-item, 3-trial, modified version of Shimamura and Jurica's (1994) version of the SOPT, and tests assessing working memory, executive function and speed. Results showed that younger adults made fewer errors on the SOPT. There was no age difference in the frequency of use of a clustering strategy. Contrary to expectations, working memory was not a good predictor of individual or age differences in SOPT performance. Instead, speed of processing, and to a lesser extent, measures of perseverations, made larger unique and overlapping contributions to the variance. The SOPT and its association, or dissociation, with other measures of working memory may be useful for research into the nature of working memory and executive function and the theoretical links between them.

Measures of fluency as predictors of incidental memory among older adults.

This study investigated fluency performance as a mediator of age-related declines in incidental memory performance as both are thought to rely on strategic retrieval processes. A large sample of community dwelling older adults completed a battery of tests assessing fluency, verbal knowledge, speed of information processing, and incidental recall. Fluency measures included initial and excluded letter fluency and the Uses for Objects Test, and they were assumed to reflect increasing reliance on strategic retrieval search. Speed emerged as the best mediator of age-related variance in incidental recall, and Uses for Objects Test performance added to the variance after controlling for verbal knowledge and speed. The results suggest that age-related decline in incidental recall is largely due to speed and the strategic search of memory.

Measurement of executive function: considerations for detecting adult age differences.

This review considers the validity and suitability of neuropsychological and other tests of executive function for the detection of adult age differences in executive function. Executive function is typically assessed using tests which have been found to be sensitive to frontal lobe dysfunction because theory links executive function with the frontal lobes. However, any age-related decline in executive function is expected to be mild, or sub-clinical, compared to the deficits shown among those with frontal lesions. Therefore, in order to detect the type of mild executive dysfunction expected among older adults we need to employ tests sensitive enough to detect any age-related deficit, yet which are not too stressful or tiring for older adults to perform. This review discusses some commonly used neuropsychological tests of executive function as well as tests devised to assess theoretical aspects of executive function. Indications are given throughout as to which tests appear to be most suitable for detecting age differences in executive function.

Toward understanding age-related memory loss in late adulthood.

BACKGROUND: While laboratory tests indicate that older adults typically perform more poorly than do younger adults on many types of memory tasks, the question arises as to whether, or to what extent, it is valid to attribute these differences to ageing per se or to some variable or class of variables that intervene between age and remembering. OBJECTIVE: The purpose of this review is to present three current views that might explain the relationship between age and remembering. They can be construed as variants on resource theories and include: the processing speed hypothesis, the executive function hypothesis, and the common cause hypothesis. METHODS: The review samples results pertinent to these hypotheses that derive from behavioural research. Studies involving various imaging techniques were considered beyond the scope of the review. RESULTS: The balance of research strongly implicates reductions in the speed of information processing as a fundamental contributor to normal age-related memory loss. Nonetheless there are circumstances where other mechanisms, such as working memory, executive function, and sensory processes, are important. CONCLUSION: Despite the phenomenological and empirical reality of age-related memory loss and the breadth of attempts to explain it, much work remains to be done to understand why it occurs. Contemporary debates about the nature and means of identifying shared and unique effects promise to shape future directions for research on memory aging.

Verbal knowledge and speed of information processing as mediators of age differences in verbal fluency performance among older adults.

Age-related declines in verbal fluency among a large sample of older adults were investigated. Background variables, verbal knowledge, and speed of processing were examined as predictors of verbal fluency and as mediators of age effects. As expected, age-related declines were greater on the excluded letter fluency task than on the initial letter fluency task. Verbal knowledge was a better predictor of initial letter fluency than speed of processing, whereas the reverse was true for excluded letter fluency. However, speed of processing accounted for more of the age-related variance in both fluency measures than the other predictors. There was no evidence of verbal knowledge compensating for age-related declines in verbal fluency. Results suggest that verbal fluency performance is well maintained in late life and that any age-related decline appears to be mainly due to declines in speed of information processing.

Predicting episodic memory performance of very old men and women: contributions from age, depression, activity, cognitive ability, and speed.

Regression models were developed to explain age-related and total variance in memory and to determine the independent contribution from general processing speed, having taken into account cognitive and noncognitive individual differences. Episodic memory was assessed for 3 tasks in a population-based sample of 951 adults comprising 515 men and 436 women (aged 70-96, M = 77.6, SD = 5.5). Correlations between age and memory accounted for 6%-9% of the variance. Hierarchical multiple regressions showed a reduction in this age-related variance by up to 94%, after entering gender, depression, health, cognitive status, activities, and speed. General processing speed was the major mediator of age-related variance in memory. Although both the age-related variance and the speed-related variance in memory were significantly reduced by prior entry of other individual differences variables for all 3 tasks, speed remained a significant mediator of remembering, and negligible differences in the residual age-related variance were observed by inclusion of other background variables.

Speed of information processing as a mediator between age and free-recall performance.

A combined experimental and individual differences approach was used to investigate the mediating role of task-specific and task-independent speed of information processing measures in the relationship between age and free-recall performance. Thirty-six younger adults (mean age = 21 years) and 36 older adults (mean age = 73 years) participated. Participants were required to encode 3 lists of words for immediate recall, by rehearsing the words aloud, twice, and 3 times. Participants' speed of information processing was assessed by 3 measures: rehearsal time, articulation speed, and scores on the Digit Symbol Substitution Test (DSST; Wechsler, 1981). Working memory was also assessed by a backward word-span measure. As predicted, younger adults recalled more words after rehearsing words 3 times rather than once, whereas older adults' recall did not increase with increasing numbers of rehearsals. Younger adults were faster on all speed-of-processing measures and had higher backward word span than did older adults. Task-independent speed of processing, measured by DSST scores and articulation speed, mediated the relationship between age and free recall. Scores on the DSST appear to reflect a fundamental difference between younger and older adults that influences recall performance.

Orienting tasks as moderators of narrative and expository text recall in adulthood.

Incidental narrative and expository prose memory of 60 older adults (M = 72 years) and 60 younger adults (M = 24 years) was assessed following orienting tasks that emphasized either relational (sentence scrambling) or individual proposition (letter deletion) information or following a control condition. Orienting tasks were done capably, but older adults took longer and made more errors on the letter-deletion task than did younger adults. Age differences in recall were observed consistently for expository texts, but for narrative texts, age differences in recall were observed only when letters were deleted. If orienting tasks overtax older adults' processing resources or emphasize shallow information, recall gains may be minimal.

A metacognitive analysis of decision making in adolescence.

Samples of 43 early (CA = 13 years) and 41 middle (CA = 15 years) adolescents were compared on three categories of metacognitive knowledge as they relate to decision making--person knowledge, task knowledge and strategy knowledge. Metacognitive knowledge was assessed using a 19-item questionnaire. Consistent with our hypothesis, middle adolescents showed significantly greater metacognitive knowledge than early adolescents on all three scales. Self-reported decision making style (using the Flinders Adolescent Decision Making Questionnaire) and decision making performance on a hypothetical scenario were also measured. Middle adolescents reported a more competent decision making style than early adolescents, while group differences on the scenario were not found. Adolescents completing the scenario scored significantly higher on all measures of decision making metacognition. Significant correlations were found between metacognitive knowledge of decision making, self-reported decision making style and performance on the decision scenario task. By middle adolescence understanding of what is involved in the activity of decision making is well developed. This growth in understanding, accompanied by changes in social domains, plays a part in decision execution and style.

Use of relational and item-specific information in remembering by older and younger adults.

The applicability to older adults of predictions from the integrated memory model, that optimal memory results from concurrent availability of relational and item-specific information, was assessed. In Experiment 1, older adults (M = 69 years) encoded related or unrelated words using rating, sorting, or both tasks. Using both tasks produced better recall than either separate task. Rating facilitated recall for related items, but sorting did not facilitate unrelated items. In Experiment 2, younger (M = 20) and older (M = 74) adults sorted or rated lists comprising categories of varying sizes. Young adults' free recall conformed to predictions, but older adults again showed facilitation mainly from rating larger categories. The stronger effects for younger adults imply that specific combinations of encoding and retrieval manipulations and materials must be considered in predicting older adults' performance.

Understanding cohort differences in cross-generational, self, and peer perceptions.

Thirty adolescent, middle-aged, and elderly people participated in a study exploring (a) their self-, inter- and intra-cohort perceptions; (b) ascribed social distance; (c) knowledge of aging; and (d) the relationships among these phenomena. Data were gathered using a Social Distance Scale, Goals of Life Index, Facts on Aging Quiz, and Aging Semantic Differentials. In general, elderly adults were the most devalued and middle-aged adults the most favored cohort. Unfavorable attitudes toward elderly people were predicted more by age-related social distance and societally induced biases than differential investments in psychosocial life tasks. Appraising one's member cohort more favorably than those outside it was paralleled by a tendency to view the self more favorably than peers. The discrepancy between societal and older individuals' views of aging suggests that the social breakdown syndrome itself may be breaking down: Older adults are moving away from a characterization of themselves as ineffective and dependent. A similar view might be engendered in younger cohorts if social distance were reduced and more attention paid to assertions of elderly adults rather than to societally induced stereotypes.

Characterizing adolescents, middle-aged, and elderly adults: putting the elderly into perspective.

Adolescents, middle-aged, and elderly adults used a Likert scale to describe an ideal, real, or typical person of either their own age group or one of the other two. On each of four dimensions of instrumentality, autonomy, acceptability, and integrity, ideal people were characterized more positively than real or typical ones. Age of neither participant or stimulus object affected these judgments. Stereotypes emerged when typical people were rated, though judgments on real people suggested little difference between elderly and middle-aged people. However, real adolescents were judged to be more unacceptable, dependent, and instrumental than were middle-aged and elderly adults. On instrumentality the age groups differed in their perceptions of each other. Adolescents and middle-aged adults perceived instrumentality to decline in old age, but the elderly did not agree. Thus attitudes reflected stereotypes when broad categorical decisions were required, but stereotypes broke down when known people were characterized.