Background: Frailty is considered highly prevalent in old age and to confer high risk for falls, disability, hospitalization, and mortality. Frailty has been considered synonymous with disability, comorbidity, and other characteristics, but it is recognized that it may have a biologic basis and be a distinct clinical syndrome. A standardized definition has not yet been established. 

Methods: To develop and operationalize a phenotype of frailty in older adults and assess concurrent and predictive validity, the study used data from the Cardiovascular Health Study. Participants were 5,317 men and women 65 years and older (4,735 from an original cohort recruited in 1989-90 and 582 from an African American cohort recruited in 1992-93). Both cohorts received almost identical baseline evaluations and 7 and 4 years of follow-up, respectively, with annual examinations and surveillance for outcomes including incident disease, hospitalization, falls, disability, and mortality. 

Results: Frailty was defined as a clinical syndrome in which three or more of the following criteria were present: unintentional weight loss (10 lbs in past year), self-reported exhaustion, weakness (grip strength), slow walking speed, and low physical activity. The overall prevalence of frailty in this community-dwelling population was 6.9%; it increased with age and was greater in women than men. Four-year incidence was 7.2%. Frailty was associated with being African American, having lower education and income, poorer health, and having higher rates of comorbid chronic diseases and disability. There was overlap, but not concordance, in the cooccurrence of frailty, comorbidity, and disability. This frailty phenotype was independently predictive (over 3 years) of incident falls, worsening mobility or ADL disability, hospitalization, and death, with hazard ratios ranging from 1.82 to 4.46, unadjusted, and 1.29-2.24, adjusted for a number of health, disease, and social characteristics predictive of 5-year mortality. Intermediate frailty status, as indicated by the presence of one or two criteria, showed intermediate risk of these outcomes as well as increased risk of becoming frail over 3-4 years of follow-up (odds ratios for incident frailty = 4.51 unadjusted and 2.63 adjusted for covariates, compared to those with no frailty criteria at baseline). 

Conclusions: This study provides a potential standardized definition for frailty in community-dwelling older adults and offers concurrent and predictive validity for the definition. It also finds that there is an intermediate stage identifying those at high risk of frailty. Finally, it provides evidence that frailty is not synonymous with either comorbidity or disability, but comorbidity is an etiologic risk factor for, and disability is an outcome of, frailty. This provides a potential basis for clinical assessment for those who are frail or at risk, and for future research to develop interventions for frailty based on a standardized ascertainment of frailty.

https://www.sharp.com/services/hospice/upload/phenotype5-13.pdf

Frailty in Older Adults Evidence for a Phenotype

Despite the concern that has been expressed about potential method biases, and the pervasiveness of research settings with the potential to produce them, there is disagreement about whether they really are a problem for researchers in the behavioral sciences. Therefore, the purpose of this review is to explore the current state of knowledge about method biases. First, we explore the meaning of the terms “method” and “method bias” and then we examine whether method biases influence all measures equally. Next, we review the evidence of the effects that method biases have on individual measures and on the covariation between different constructs. Following this, we evaluate the procedural and statistical remedies that have been used to control method biases and provide recommendations for minimizing method bias.

Sources of Method Bias in Social Science Research and Recommendations on How to Control It

because observed behavior is the result of interactions between environmental factors and genes during the extended period of development. Therefore, to better understand expert and exceptional performance, we must require that the account specify the different environmental factors that could selectively promote and facilitate the achievement of such performance. In addition, recent research on expert performance and expertise (Chi, Glaser, & Farr, 1988; Ericsson & Smith, 1991a) has shown that important characteristics of experts' superior performance are acquired through experience and that the effect of practice on performance is larger than earlier believed possible. For this reason, an account of exceptional performance must specify the environmental circumstances, such as the duration and structure of activities, and necessary minimal biological attributes that lead to the acquisition of such characteristics and a corresponding level of performance. An account that explains how a majority of individuals can attain a given level of expert performance might seem inherently unable to explain the exceptional performance of only a small number of individuals. However, if such an empirical account could be empirically supported, then the extreme characteristics of experts could be viewed as having been acquired through learning and adaptation, and studies of expert performance could provide unique insights into the possibilities and limits of change in cognitive capacities and bodily functions. In this article we propose a theoretical framework that explains expert performance in terms of acquired characteristics resulting from extended deliberate practice and that limits the role of innate (inherited) characteristics to general levels of activity and emotionality. We provide empirical support from two new studies and from already published evidence on expert performance in many different domains.

/pdf/the-role-of-deliberate-practice-in-the-acquisition-of-expert-3j9768t5su.pdf

The role of deliberate practice in the acquisition of expert performance.

Recent studies of eye movements in reading and other information processing tasks, such as music reading, typing, visual search, and scene perception, are reviewed. The major emphasis of the review is on reading as a specific example of cognitive processing. Basic topics discussed with respect to reading are (a) the characteristics of eye movements, (b) the perceptual span, (c) integration of information across saccades, (d) eye movement control, and (e) individual differences (including dyslexia). Similar topics are discussed with respect to the other tasks examined. The basic theme of the review is that eye movement data reflect moment-to-moment cognitive processes in the various tasks examined. Theoretical and practical considerations concerning the use of eye movement data are also discussed.

/pdf/eye-movements-in-reading-and-information-processing-20-years-3z5ay8hdwc.pdf

Eye movements in reading and information processing: 20 years of research.

A theory is proposed to account for some of the age-related differences reported in measures of Type A or fluid cognition. The central hypothesis in the theory is that increased age in adulthood is associated with a decrease in the speed with which many processing operations can be executed and that this reduction in speed leads to impairments in cognitive functioning because of what are termed the limited time mechanism and the simultaneity mechanism. That is, cognitive performance is degraded when processing is slow because relevant operations cannot be successfully executed (limited time) and because the products of early processing may no longer be available when later processing is complete (simultaneity). Several types of evidence, such as the discovery of considerable shared age-related variance across various measures of speed and large attenuation of the age-related influences on cognitive measures after statistical control of measures of speed, are consistent with this theory.

http://www.anitacrawley.net/Resources/Articles/salthouse%20The%20Processing%20Speed%20Theory%20of%20Adult%20Age%20Differences%20in%20Cognition.pdf

The processing-speed theory of adult age differences in cognition.

Eight experiments were conducted in which young adults and older adults were asked to report the latest value of 1 of several continuously changing numeric or spatial variables. Accuracy of reporting the current value of the target variable was lower with increases in the number of potentially relevant variables and with increases in the number of required processing operations. Young and older adults exhibited similar effects of the number of potentially relevant variables (hypothesized to be sensitive to the structural capacity of working memory) and of the number of required processing operations (hypothesized to be sensitive to the operational capacity of working memory), but older adults were generally less accurate than young adults. Working memory is generally distinguished from earlier notions of short-term memory by an emphasis on the simultaneous storage and processing of information in working memory, as opposed to a concern primarily with the storage of information in short-term memory (e.g., Baddeley, 1986; Craik & Rabinowitz, 1984; Daneman & Carpenter, 1980). It has recently been suggested (cf. Carpenter & Just, 1989; Salthouse & Mitchell, 1989) that working memory may have at least two distinct capacities, structural and operational, with the former referring to capacity in terms of "the number of distinct informational units that can be remembered at any given time" and the latter to capacity in terms of "the number of processing operations that can be performed while still preserving the products of earlier operations" (Salthouse & Mitchell, 1989, p. 18). Carpenter and Just (1989) and Salthouse (1982) have proposed analogies to clarify the contrast between static or structural, and dynamic or operational, capacities. A hospital was used as the basis of the analogy by Carpenter and Just, with static capacity likened to the number of surgical theaters and dynamic capacity interpreted in terms of the number of surgical operations that can be performed in a given period. Salthouse (1982, p. 180-181) contrasted the structural capacity of a banquet hall, expressed as the maximum number of diners that could be accommodated at a single time, with the operational capacity of a fast-food restaurant, as reflected by the number of meals that could be served in a specified period. With respect to working memory, the key distinction in both analogies is between capacity expressed as the maximum number of items that can be remembered and capacity reflected in terms of the

https://www.researchgate.net/profile/Timothy_Salthouse/publication/21127371_Effects_of_adult_age_on_structural_and_operational_capacities_in_working_memory/links/00b7d537c69237e2ea000000.pdf

Effects of adult age on structural and operational capacities in working memory.

Previous research has established that a large proportion of the adult age-related variance in various measures offluid or process cognition is reduced when statistical control procedures such as hierarchical regression are used to eliminate variation in measures ofperceptual speed. This finding was confirmed in the present study and was extended to include paired-associate and free-recall measures of memory in addition to measures of reasoning and spatial abilities. Most of the speed mediation was associated with speed measures requiring cognitive operations such as comparison or substitution instead of merely motor responses such as copying symbols or drawing lines. These results suggest that the rate of performing elementary cognitive operations is an important proximal mediator ofthe adult age differences in several types ofcognitive tasks. Inspired largely by ideas of Birren (e.g., 1955,1965,1974), Salthouse 0985a) proposed that the adult age differences in certain measures of cognitive functioning might be partially mediated by age-related reductions in the speed ofexecuting relevant mental operations. The evidence available at that time was rather weak, because no published studies had been explicitly designed to investigate this hypothesis. Most of the data relevant to the hypothesis were obtained by locating published articles reporting correlations among age, a measure of processing speed, and a measure of cognition (or studies by Salthouse containing the relevant data), and then computing partial correlations between age and the cognitive measure after partialing out the measure of speed. Only a few data sets with the necessary information could be identified, and the samples were often small and usually involved two extreme age groups rather than a continuous range of ages. Furthermore, in all cases the relevant constructs were assessed with a single measure rather than with potentially more reliable and valid multiple measures. Despite these limitations, the hypothesis received some support because statistical control of the measure ofspeed frequently resulted in an appreciable reduction in the magnitude of the relation between age and the measure of cognition.

Speed Mediation of Adult Age Differences in Cognition.

Two studies were conducted to investigate whether a meaningful task-switching construct could be identified and, if so, to determine how it was related to measures of higher order cognition and to adult age. Both studies revealed that measures of task switching were moderately correlated across different combinations of tasks and that a switching construct could be distinguished from a construct reflecting processing speed. The results of the 2nd study revealed that although the task-switching construct was related to age and to measures of episodic memory, inductive reasoning, and spatial visualization, most of the relations between the switching construct and both age and other measures of cognition were shared with other variables.

Relation of Task Switching to Speed, Age, and Fluid Intelligence

http://library.um.ac.id/free-contents/downloadpdf.php/buku/adult-cognition-an-experimental-psychology-of-human-aging-timothy-a-salthouse-18335.pdf

Adult cognition : an experimental psychology of human aging / Timothy A. Salthouse

Two studies were conducted to determine the relations among age, motor speed, perceptual speed, and 3 measures of cognitive performance: study time, decision time, and decision accuracy. Each study involved over 240 adults between I 8 and over 80 years of age who all performed a battery of tests, including computer-administered tests of memory, reasoning, and spatial ability. The results indicated that (a) increased age was associated with lower accuracy as well as with longer study time and decision time and (b) some ofthe relations between age and decision accuracy and between age and decision time appear to be mediated by a slower rate ofexecuting cognitive operations. Considerable evidence now exists indicating that a large proportion ofthe age-related variance in many different cognitive variables is shared with a measure of perceptual speed. Among the most pertinent results are the findings that the age-related diffbrences in various measures of cognitive functioning are greatly reduced when statistical control procedures are used to adjust for differences in perceptual speed. As an illustration of this phenomenon, Thble I in Salthouse (1993b) contains 44 comparisons across a wide range of cognitive variables. Age was associated with a mean of l6.2Vo of the total variance in the variables, but after the variance associated with measures of perceptual speed was held constant, age was associated with only 3.6Vo ofthe variance in the cognitive variables.

The Nature of the Influence of Speed on Adult Age Differences in Cognition.

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