Biomedical subjects

Paolo Ghisletta

Publications and source records attributed to Paolo Ghisletta.

7 recordsLinked to original sources

PubMed2006

On the power of multivariate latent growth curve models to detect correlated change.

We evaluated the statistical power of single-indicator latent growth curve models (LGCMs) to detect correlated change between two variables (covariance of slopes) as a function of sample size, number of longitudinal measurement occasions, and reliability (measurement error variance). Power approximations following the method of Satorra and Saris (1985) were used to evaluate the power to detect slope covariances. Even with large samples (N = 500) and several longitudinal occasions (4 or 5), statistical power to detect covariance of slopes was moderate to low unless growth curve reliability at study onset was above .90. Studies using LGCMs may fail to detect slope correlations because of low power rather than a lack of relationship of change between variables. The present findings allow researchers to make more informed design decisions when planning a longitudinal study and aid in interpreting LGCM results regarding correlated interindividual differences in rates of development.

Aging↗

PubMed2006

Does activity engagement protect against cognitive decline in old age? Methodological and analytical considerations.

The literature about relationships between activity engagement and cognitive performance is abundant yet inconclusive. Some studies report that higher activity engagement leads to lower cognitive decline; others report no functional links, or that higher cognitive performance leads to less decline in activity engagement. We first discuss some methodological and analytical features that may contribute to the divergent findings. We then apply a longitudinal dynamic structural equation model to five repeated measurements of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old. Performance on perceptual speed and verbal fluency tasks was analyzed in relation to six different activity composite scores. Results suggest that increased media and leisure activity engagement may lessen decline in perceptual speed, but not in verbal fluency or performance, whereas cognitive performance does not effect change in activity engagement.

Activities of Daily Living↗

PubMed2005

Social participation attenuates decline in perceptual speed in old and very old age.

Does an engaged and active lifestyle in old age alleviate cognitive decline, does high cognitive functioning in old age increase the possibility of maintaining an engaged and active lifestyle, or both? The authors approach this conundrum by applying a structural equation model for testing dynamic hypotheses, the dual change score model (J. J. McArdle & F. Hamagami, 2001), to 3-occasion longitudinal data from the Berlin Aging Study (Time 1: n=516, age range=70-103 years). Results reveal that within a bivariate system of perceptual speed and social participation, with age and sociobiographical status as covariates, prior scores of social participation influence subsequent changes in perceptual speed, while the opposite does not hold. Results support the hypothesis that an engaged and active lifestyle in old and very old age may alleviate decline in perceptual speed.

Aged↗

PubMed2005

A dynamic investigation of cognitive dedifferentiation with control for retest: evidence from the Swiss Interdisciplinary Longitudinal Study on the Oldest Old.

Empirical examinations of the hypothesis of dedifferentiation of cognitive abilities in old and very old age (a) do not account for possible retest effects, which consequently may yield biased estimates of age effects, and (b) focus on time-independent relations (e.g., number of latent constructs, correlations between latent or measured variables). The authors applied a structural equation model with statistical control for retest effects to investigate the dynamic relations between a marker of perceptual speed (cross out) and a marker of verbal fluency (category-fruits). Longitudinal data are from 5 waves of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old (N = 377, baseline age range = 79.5- 84.5 years). The authors found that, independently of retest effects, performance on the cross-out task affected changes in performance on the category task while the opposite did not hold true. This analytical technique could be applied to various markers of broad fluid-mechanic and broad crystallized-pragmatic components of cognition.

Aged↗

PubMed2003

The fate of cognition in very old age: six-year longitudinal findings in the Berlin Aging Study (BASE).

The authors report full-information longitudinal age gradients in 4 intellectual abilities on the basis of 6-year longitudinal changes in 132 individuals (mean age at T1 = 78.27, age range = 70-100) from the Berlin Aging Study. Relative to the cross-sectional parent sample (N = 516, mean age at T1 = 84.92 years), this sample was positively selected because of differential mortality and experimental attrition. Perceptual speed, memory, and fluency declined with age. In contrast, knowledge remained stable up to age 90, with evidence for decline thereafter. Age gradients were more negative in old old (n = 66, mean age at T1 = 83.04) than in old (n = 66, mean age at T1 = 73.77) participants. Rates of decline did not differ reliably between men and women or between participants with high versus low life-history status. They conclude that intellectual development after age 70 varies by distance to death, age, and intellectual ability domain.

Age Factors↗

PubMed2003

Age-based structural dynamics between perceptual speed and knowledge in the Berlin Aging Study: direct evidence for ability dedifferentiation in old age.

According to 2-component theories of intelligence, negative cross-sectional age gradients in mechanic (broad Gf) and pragmatic (broad Gc) cognitive components reflect the increasing constraining of the former in the expression and integrity of the latter component. The authors examined this widely held but untested assumption by applying a recently proposed dynamic structural modeling technique, the bivariate dual change score model, to longitudinal data from the Berlin Aging Study (N = 516, age range = 70-103 years). Mechanics and pragmatics were indexed by perceptual speed and knowledge, respectively. As hypothesized, results indicated that changes in knowledge are dominated by perceptual speed and offered strong support for the notion of "mechanization" of pragmatic abilities in old and very old age.

Aged↗

PubMedDate not supplied

Static and dynamic longitudinal structural analyses of cognitive changes in old age.

BACKGROUND: Among the main data-analytical advances of recent decades are Latent Growth Models (LGM) and Multilevel Models (MLM) for the analysis of longitudinal data. OBJECTIVE: We discuss the relative advantages and disadvantages of the two analytical methods and offer some practical guidelines concerning the choice between LGM and MLM based on (a). completeness and balance of the data, (b). theoretical functional form of change examined, (c). examination of the error structure, (d). theoretical relations among differential level effects and differential change effects, and (e). role of time-invariant covariates. METHODS: To discuss LGM and MLM, we provide illustrations from applications to the Berlin Aging Study (BASE) and the Swiss Interdisciplinary Longitudinal Study on the Oldest Old (SWILSO-O). RESULTS: As predicted by two-component theories of lifespan cognition, performance on a vocabulary test (indicator of broad crystallized intelligence) did not decline over time, while scores on a digit letter test (indicator of broad fluid intelligence) decreased over 6 years. Differential level effects were obtained on both variables, while average and differential change effects were obtained only for the digit letter test. In a second set of analyses, we tested the error-free effect that a broad fluid intelligence indicator exerted on the latent yearly change in a broad crystallized intelligence indicator, and vice versa. In both data sets we obtained strong evidence for a more reliable effect of the fluid indicator on the change in the crystallized indicator. This evidence provided support for the dedifferentiation hypothesis of cognitive abilities in very old age. CONCLUSIONS: New insights into cognitive aging phenomena can be gained with proper applications of LGM and MLM. We posit that the choice between LGM and MLM and their specification rests on theoretical and empirical motives to be defined a priori.

Aging↗