Mary A. Luszcz

Effect of social networks on 10 year survival in very old Australians: the Australian longitudinal study of aging

Study objectives: To examine if social networks with children, relatives, friends, and confidants predict survival in older Australians over 10 years after controlling for a range of demographic, health, and lifestyle variables. Design: Prospective longitudinal cohort study (the Australian longitudinal study of aging) Setting: Adelaide, South Australia. Participants: 1477 persons aged 70 years or more living in the community and residential care facilities. Main results: After controlling for a range of demographic, health, and lifestyle variables, greater networks with friends were protective against mortality in the 10 year follow up period. The hazard ratio for participants in the highest tertile of friends networks compared with participants in the lowest group was 0.78 (95%CI 0.65 to 0.92). A smaller effect of greater networks with confidants (hazard ratio = 0.84; 95%CI  = 0.71 to 0.98) was seen. The effects of social networks with children and relatives were not significant with respect to survival over the following decade. Conclusions: Survival time may be enhanced by strong social networks. Among older Australians, these may be important in lengthening survival.

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.

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.

Predicting Driving Cessation over 5 Years in Older Adults: Psychological Well-Being and Cognitive Competence Are Stronger Predictors than Physical Health

Objectives: To examine psychological, medical, and sensorimotor risk factors that predict driving cessation in older adults.

An 8-year prospective study of the relationship between cognitive performance and falling in very old adults.

OBJECTIVES: To determine whether cognitive performance, as distinct from cognitive impairment, predicts falling during an 8‐year follow‐up in a community‐based sample of very old adults and to evaluate how cognitive change is associated with falling.

A Latent Growth Curve Analysis of Late-Life Sensory and Cognitive Function over 8 Years: Evidence for Specific and Common Factors Underlying Change

Correlations among rates of change in sensory and cognitive functioning in adulthood were evaluated. Measures of Vision, Hearing, Memory, Speed and Verbal ability were obtained in 1992, 1994, and 2000 in the Australian Longitudinal Study of Aging (N = 2,087 at baseline). Data from 1,823 participants who undertook at least 1 clinical assessment were analyzed using latent growth curve models. A significant moderate-sized association between rates of change in Memory and Vision was found. This remained after statistically controlling for the effects of age, gender, education, self-rated health, medical conditions, and depressive symptoms. Rate of change in Hearing was weakly associated with rate of change in Memory. The results support a theory incorporating a major role for unique factors in addition to common factors underlying sensory and cognitive change in old age.

The Executive Decline Hypothesis of Cognitive Aging: Do Executive Deficits Qualify as Differential Deficits and Do They Mediate Age-Related Memory Decline?*

This paper reports the results of two studies which investigated whether aging is associated with a differential deficit in executive function, compared with deficits in general cognitive ability (Wechsler Adult Intelligence Scale-Revised performance). Further, the studies investigated the specificity of the executive decline hypothesis of memory and aging by examining whether declines in executive function mediate age-related memory decline over and above the variance in memory accounted for by general cognitive ability. The results of Study 1 showed no consistent evidence of a differential decline in executive function among a sample of participants aged between 18 and 75 years. The results of Study 2 indicated a differential decline in one indicator of executive function, the Modified Card Sorting Test, among an older sample aged between 60 and 89 years. Both studies demonstrated that measures of executive function accounted for age-related variance in free recall, recognition, and serial recall, even after controlling for general cognitive ability. However, in Study 1, once variance attributed to speed of processing was taken into account, executive function did not contribute further to the age-related variance.

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.

Successful Aging in the Australian Longitudinal Study of Aging: Applying the MacArthur Model Cross–Nationally

Wide variation in the experience of aging is increasingly recognized and models for identifying groups based on how “successfully” individuals are aging have taken many forms. This study used the criteria developed in the MacArthur studies on successful aging to identify subgroups with higher, intermediate, or lower levels of function, and to compare them across a range of other domains. Data were drawn from the Australian Longitudinal Study of Aging (ALSA) in Adelaide, Australia, which is a population–based, bio–psycho–social study of a cohort of 1947 adults aged 70 years or more. Six waves have been conducted, between 1992 and 2000. At waves 1 and 3, an extensive personal interview and self–complete questionnaires were administered and objective physical and psychological functioning assessed. Eight–year mortality was also examined. Results showed risk and protective effects of successful aging for physical functioning and performance, lifestyle, cognition, affect, and personality. The findings confirm that people age with differing degrees of success and those aging most successfully not only live longer, but also experience a better quality of life. The MacArthur model proved useful for this cross–national comparison of determinants and outcomes of “successful” aging.

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.