Dispersion in Cognitive Ability as a Function of Age: A Longitudinal Study of an Elderly Community Sample

This longitudinal study investigated whether age is associated with increased dispersion among major domains of cognitive ability. Three samples were examined: the full sample of 760 elderly community dwellers aged 70 years and older who were tested in 1990; a subset of the original sample who died between testing occasions; and the sample of 426 who survived with full data sets in 1994 (followed up for a mean 3.5 years). Dispersion, as measured by the within-individual standard deviation of ability scores and by the within-individual deviations from crystallized intelligence for speed, memory and spatial functioning, was significantly correlated with age in all three samples at Wave 1 and at Wave 2 (for the longitudinal sample). The rate at which dispersion increased was not significantly correlated with age. In a more detailed analysis of the 426 survivors, dispersion as a function of age was similar for demented persons within this sample, those without dementia, those with poor and excellent educational levels, and those with a physical disability. Activities of daily living was a predictor of larger-than-average changes in dispersion – but not age, education, or activity. Greater dispersion was associated with faster deterioration in memory and speed performance. Contrary to some recent reports, there was evidence for greater within-individual variability among cognitive domains in older individuals.     

An analysis of diversity in the cognitive performance of elderly community dwellers: individual differences in change scores as a function of age.

This longitudinal study investigated whether age is associated with increases in interindividual variability across 4 ability domains using a sample of 426 elderly community dwellers followed over 3.5 years. Interindividual variability in change scores increased with age for memory, spatial functioning, and speed but not for crystallized intelligence for the full sample and in a subsample that excluded dementia or probable dementia cases. Hierarchical regression analyses indicated that being female, having weaker muscle strength, and having greater symptoms of illness and greater depression were associated with overall greater variability in cognitive scores. Having a higher level of education was associated with reduced variability. These findings are consistent with the view that there is a greater range of responses at older ages, that certain domains of intelligence are less susceptible to variation than others and that variables other than age affect cognitive performance in later life.     

Effectiveness of antidepressants: an evidence myth constructed from a thousand randomized trials?

Antidepressants, in particular newer agents, are among the most widely prescribed medications worldwide with annual sales of billions of dollars. The introduction of these agents in the market has passed through seemingly strict regulatory control. Over a thousand randomized trials have been conducted with antidepressants. Statistically significant benefits have been repeatedly demonstrated and the medical literature is flooded with several hundreds of "positive" trials (both pre-approval and post-approval). However, two recent meta-analyses question this picture. The first meta-analysis used data that were submitted to FDA for the approval of 12 antidepressant drugs. While only half of these trials had formally significant effectiveness, published reports almost ubiquitously claimed significant results. "Negative" trials were either left unpublished or were distorted to present "positive" results. The average benefit of these drugs based on the FDA data was of small magnitude, while the published literature suggested larger benefits. A second meta-analysis using also FDA-submitted data examined the relationship between treatment effect and baseline severity of depression. Drug-placebo differences increased with increasing baseline severity and the difference became large enough to be clinically important only in the very small minority of patient populations with severe major depression. In severe major depression, antidepressants did not become more effective, simply placebo lost effectiveness. These data suggest that antidepressants may be less effective than their wide marketing suggests. Short-term benefits are small and long-term balance of benefits and harms is understudied. I discuss how the use of many small randomized trials with clinically non-relevant outcomes, improper interpretation of statistical significance, manipulated study design, biased selection of study populations, short follow-up, and selective and distorted reporting of results has built and nourished a seemingly evidence-based myth on antidepressant effectiveness and how higher evidence standards, with very large long-term trials and careful prospective meta-analyses of individual-level data may reach closer to the truth and clinically useful evidence.     

Predicting anxiety and depression from personality: is there a synergistic effect of neuroticism and extraversion?

In a longitudinal study of college students, B. S. Gershuny and K. J. Sher (1998) found that high neuroticism and low extraversion had a synergistic effect in predicting anxiety and depression 3 years later. This article attempted to replicate their finding using data from 2 community samples: (a) a cross-sectional survey of 2,677 persons aged 18-79 years, and (b) a longitudinal study in which 441 persons aged 70 or older were followed over 3-4 years. Both studies found that neuroticism predicted anxiety and depression, but there were no Neuroticism x Extraversion interaction effects. These results cast doubt on the generalizability of the original findings.     

The Canberra Longitudinal Study: Design,Aims, Methodology,Outcomes and Recent Empirical Investigations

The first section of this paper describes methodology and major cognitive outcomes of the Canberra Longitudinal Study (CLS). This community study of 1045 Australians aged 70 years or over commenced in 1990. Participants were reassessed on three subsequent occasions. Its major themes were investigations of prevalence of dementia and depression, risk factors, inter-individual variability and instrument development. Over 60 papers arising from the study have been published.

The second section of this paper describes the use of a Factor of Curves (FOC) latent growth model to examine the existence of a common factor responsible for age-related deterioration in cognitive and non-cognitive processes. This analysis is a logical progression in a series of investigations using the Canberra Longitudinal Study into risk factors and correlates of cognitive change using structural equation modeling techniques. The FOC model is described and is used to explore the nature of an hypothesized common factor and to determine its relationship with age, gender, education, pre-morbid intelligence and to the ApoE genotype. Latent growth models were developed for each of reaction time, Symbol Letter Modalities Test (SLMT), Grip strength, self-reported Sensory disability and memory from three waves of data. Second-order latent level slope factors were established based on the individual factor growth curve models. Although a common factor model could be fitted to the data, there is little support that it represents a single common cause.     

The 9th annual INDUS-EM 2013 Emergency Medicine Summit, “Principles,Practices, and Patients,” a level one international meeting,Kerala University of Health Sciences and Jubilee Mission Medical College and Research Institute,Thrissur, Kerala,India, October 23–27, 2013

INDUS-EM is India’s only level one conference imparting and exchanging quality knowledge in acute care. Specifically, in general and specialized emergency care and training in trauma, burns, cardiac, stroke, environmental and disaster medicine. It provides a series of exchanges regarding academic development and implementation of training tools related to developing future academic faculty and residents in Emergency Medicine in India. The INDUS-EM leadership and board of directors invited scholars from multiple institutions to participate in this advanced educational symposium that was held in Thrissur, Kerala in October 2013.     

Use of the Transparent Bipolar Inventory to measure the big-five personality factors in an epidemiological survey of the elderly

Goldberg (1992) developed the Transparent Bipolar Inventory (TBI) as a set of simple factor markers for the big-five personality traits. In the present study, the TBI was completed by 534 elderly persons participating in the second wave of a longitudinal epidemiological study. Confirmatory factor analysis of the TBI items showed that the five-factor model provided an acceptable, but not impressive, fit to the data. In contrast to Goldberg's analyses with university students, the factors in this sample were substantially correlated. The fitting of a model to account for between-factor correlations demonstrated the existence of an important general factor underlying responses to nearly all the TBI items. This general factor may represent an artefact of scale usage. While our results provide some support for Goldberg's five-factor structure, it would be premature to promote the TBI scales as markers of major personality dimensions.     

Cognitive outcomes of pediatric stroke

A limited number of longitudinal studies have investigated long-term neuropsychological development in the pediatric stroke population. This study retrospectively examines cognitive outcomes in 41 children with a history of stroke, with reference to age at stroke, laterality, region and mechanism of stroke. In the course of recovery, neuropsychological measures of intellectual functioning and memory were administered at two time points, whilst executive functioning, attention and academic skills were administered at one time point. As predicted, children with stroke performed significantly worse compared to normative expectations on all neuropsychological measures. Up to two thirds of children scored in the borderline impaired and impaired ranges on at least one domain of cognition. Performance on intellectual and memory assessment remained relatively stable over time. Younger age at stroke was found to be associated with poorer intellectual functioning. No effects of laterality of stroke on neuropsychological performance over time were found. Children with subcortical stroke demonstrated a greater improvement in immediate memory over time than children with cortical stroke. These findings reveal that children with stroke display long-term cognitive difficulties that typically remain stable over time. Attention and academic skills are particularly vulnerable to impairment. Further evidence that age at stroke is a significant factor in terms of cognitive outcome is provided, in support of the “early vulnerability” position.