Socioeconomic deprivation and the development of neuropsychological functions: A study with “street children” in Ecuador

Socioeconomic status (SES) is known to have a considerable influence on the development of neuropsychological functions. In particular there is strong evidence for less efficient development of prefrontal-cortex-related functions in children raised in low-SES households. “Street children” are a common feature of low SES in many low- and middle-income countries, and some researchers have suggested that the unique life experiences of street children may drive their neurocognitive development. This study compares a group of 36 former street children in Quito, Ecuador with a control group of 26 never street-connected schoolchildren. All children were assessed with a range of neuropsychological tests. Although the street children group performed significantly below the level of the control group on all measures, they did not demonstrate a generalized lower ability. By controlling the effects of fluid intelligence it was found that there are relatively independent effects on visuospatial ability and executive planning ability. Furthermore, the executive function test scores in general are significantly less affected than the other cognitive functions and may be temporary effects caused by recent substance abuse within the street child sample. The findings generally support results from other countries suggesting that low SES is associated with negative effects on neuropsychological development. However, they also suggest that the local social and economic context, such as in the case of street children, might mitigate the harmful effects of low SES on the development of some executive functions.     

Influence of memory strategies on memory test performance: A study in healthy and pathological aging

ABSTRACT

The ability to generate memory strategies is a key factor in the performance of episodic memory tasks. Whether the ability to generate memory strategies exerts an influence in the performance of memory tests in the elderly population is still a matter of debate. Here we present results from an experimental memory task (Test of Memory Strategies, TMS), comprised of five lists of words starting from an incidental learning task, and four more lists which progressively gain in their external organization of the material, reducing the necessity of mobilizing complex memory strategies. TMS has been applied to four groups of elderly patients (amnestic Mild Cognitive Impairment – aMCI, multidomain (mMCI), and Vascular Cognitive Impairment – VCI and Depression) and a healthy aging group. In conditions with low organization of the material, the mMCI and VCI groups (both showing a greater executive function impairment) have shown lower performance. However, as the material was progressively organized, they improved their performance. The aMCI group showed similar performance to the control group at the lower level of external organization but did not improve performance in conditions with a high level of external organization. The mMCI and VCI groups showed lower performance on all TMS conditions compared with controls. Discriminant analysis revealed 90% sensitivity and specificity to differentiate between groups based on TMS conditions. These results indicate how executive functions influence performance on memory tasks in elderly subjects with different neuropsychological profiles.     

A Two-Year Longitudinal Study of Neuropsychological and Cognitive Performance in Relation to Behavioral Problems and Competencies in Elementary School Children

Despite interest in early neuropsychological status as a possible contributor to children's behavioral development, prospective longitudinal investigations of neuropsychological measures in relation to later behavioral outcomes in childhood are few. A 2-year longitudinal study in a nonselected childhood sample is reported. The study tested the influence of early neuropsychological performance (verbal fluency, mental inhibitory control, and visual spatial ability) on later childhood behavioral problems and social competency. Regular education children (n = 235) were assessed at three time points 1 year apart. To control for autocorrelation of outcome measures, Time 1 behavior was partialed while testing the effects of Time 1 neuropsychological scores on Time 3 outcome. To control for autocorrelation of neuropsychological scores, Time 2 scores were partialed while testing the predictive effect of Time 1 scores on Time 3 outcome. Both sets of regression models suggested modest but statistically significant effects for inhibitory control and verbal fluency, but not IQ, reading, or visual spatial ability, on behavioral outcome. Study results are consistent with a modest causal effect of selected neuropsychological skills on later behavioral adjustment. The findings support theories that implicate subtle neuropsychological dysfunction in the development of behavioral problems in childhood.     

The role of the executive functions in school achievement at the end of Grade 1

The aim of this study was to determine the role of executive functions (EFs) in early school achievement when a variety of potential confounding factors were controlled. Measures of EF (inhibition, flexibility, and working memory) and school readiness were administered to a sample of 85 kindergartners (39 boys and 46 girls, 5-6 years old). School achievement was then assessed at the end of Grade 1. Results show math and reading/writing skills at the end of Grade 1 to be associated with kindergarten EFs. Only working memory contributed uniquely to the variance in school achievement after all covariates (preacademic abilities, affective variables, and family variables) were controlled and, even then, only with respect to math skills. On the other hand, working memory and inhibition had an indirect effect on reading/writing skills via anger-aggression. EF implication in school achievement is discussed in terms of task demands and child age.     

Aging of the planning process: the role of executive functioning

This study tested whether the aging of executive functioning is linked to the decline in planning performance. Participants were divided into three groups: group 1 composed of 15 adults with a mean age of 22.7 years, group 2 composed of 15 adults with a mean age of 68.1 years and group 3 composed of 16 adults with a mean age of 78.75 years. Each participant took tests for shifting, inhibition, updating and processing speed. Planning was evaluated by the Tower of Hanoi task with 3 and 4 disks. Analyses of variance showed a main age effect on the many executive functioning and planning measures assessed. Analyses of regression indicated that combined processing speed and shifting accounted for 58.33% of performance on the 3-disk version, while processing speed accounted for only 36.86% of performance on the 4-disk version. These results are discussed in relation to two levels of the planning process: formulation and execution.     

State of Multicultural Neuropsychological Assessment in Children: Current Research Issues

Scientific attention to cultural considerations in child neuropsychological assessment has not developed parallel to the focus these issues have received in adult and elderly neuropsychological assessment. There are limited data on the presence, magnitude, etiology, and implications of culture-related differences in cognitive test performance among children. This preliminary report reviews the available empirical literature on the current state of multicultural neuropsychological assessment in children. The review identified articles by searching PubMed and PsycINFO databases, and the tables of contents of Developmental Neuropsychology and Child Neuropsychology from 2003-2008. Of the 1,834 abstracts reviewed, ten papers met inclusion criteria for the review. Five studies were completed in America; four of these compared performance between ethnic groups while the fifth examined neighborhood level poverty indicators exclusively within African-American children. Of the five international studies, all established local normative data and/or were exploratory investigations of neuropsychological functions in specific cultural groups, including Taiwanese infants, South African youth, and bilingual British children. Taken together, the results yield important clinical and research data that begin to inform many of the complex and fascinating mechanisms by which ethnic identity and culture impact cognitive development and the neuropsychological assessment of children. A critique of the existing literature and directions for future research are provided.     

Clarifying the role of impulsivity in dietary restraint: A structural equation modeling approach

This study was designed to clarify the relationship between the four dimensions of impulsivity in Whiteside and Lynam’s (2001) model and the two aspects of dietary restraint (Concern for Dieting and Weight Fluctuation) in a non-clinical sample. Data were collected from a volunteer community sample (N = 216) of women who responded to two self-report instruments related to impulsivity (UPPS Impulsive Behavior Scale, Whiteside & Lynam, 2001) and dietary restraint (Restraint Scale, Polivy, Herman, & Warsh, 1978). A structural equation model was tested. The model provided a good fit to the data (χ²/df = 1.64, p < .0001, RMSEA = 0.054, 90% CI = 0.050–0.058, p-value for test of close fit (RMSEA > 0.05) = .035) and revealed that Concern for Dieting was positively related to Urgency (standardized β = 0.25, p < .01). Weight Fluctuation was related to lack of Perseverance (standardized β = 0.25, p < .01) and tended to relate to Sensation Seeking (standardized β = 0.17, p = .056). Urgency and lack of Perseverance were found to play a significant role in predicting Concern for Dieting and Weight Fluctuation.     

A latent variable approach to executive control in healthy ageing

It is a well-established finding that the central executive is fractionated in at least three separable component processes: Updating, Shifting, and Inhibition of information (Miyake et al., 2000). However, the fractionation of the central executive among the elderly has been less well explored, and Miyake's et al. latent structure has not yet been integrated with other models that propose additional components, such as access to long-term information. Here we administered a battery of classic and newer neuropsychological tests of executive functions to 122 healthy individuals aged between 48 and 91 years. The test scores were subjected to a latent variable analysis (LISREL), and yielded four factors. The factor structure obtained was broadly consistent with Miyake et al.'s three-factor model. However, an additional factor, which was labeled 'efficiency of access to long-term memory', and a mediator factor ('speed of processing') were apparent in our structural equation analysis. Furthermore, the best model that described executive functioning in our sample of healthy elderly adults included a two-factor solution, thus indicating a possible mechanism of dedifferentiation, which involves larger correlations and interdependence of latent variables as a consequence of cognitive ageing. These results are discussed in the light of current models of prefrontal cortex functioning.     

Modeling the Ecological Validity of Neurocognitive Assessment in Adults with Acquired Brain Injury

Neuropsychologists are increasingly asked to make judgments regarding treatment options and rehabilitation strategies in addition to evaluating the degree and scope of neuropsychological impairment following acquired brain injuries. The capacity to make informed clinical decisions relies upon research investigating the relationships between neuropsychological and psychosocial status (i.e., ecological validity). Unfortunately, much of this research employs exploratory analyses, an approach that can lead to theoretical ambiguity and ad-hoc interpretations. The current availability and accessibility of analytical tools, like structural equation modeling (SEM), however, permits the testing of specific hypotheses regarding ecological validity and promotes a-priori theory development. In the current study, a theory-driven model of the ecological validity of a neurocognitive assessment was tested against data obtained from individuals with acquired brain injury using SEM. The results provide confirmatory evidence for the ecological validity of neurocognitive constructs and empirical support for a theory-driven analytical approach to ecological validity research.     

A reappraisal of the relationship between span memory and intelligence via “best evidence synthesis”

This paper examines the relationship between span memory [e.g., immediate memory, short-term memory (STM), simple span] and general ability (g) though a reanalysis of two data sets [Christal, R. E. (1959). Factor analytic study of visual memory. Psychological Monographs: General and Applied, 72 (13, Whole No. 466); Kelley, H.P. (1964). Memory abilities: A factor analysis. Psychometric Monographs, No. 11]. Because of their large sample sizes and the multiple measures used to identify each construct, the Christal and Kelley studies were examined within a “best evidence synthesis” framework. Modern structural equation modeling (SEM) techniques were used to examine the relationship between immediate memory and g. Results indicated that in both studies, the relationship between immediate memory and g was quite substantial (.71 and .83), and that this relationship was essentially reduced by half when the common content variance of the tests was accounted for (e.g., verbal, spatial, numerical). Results are discussed within the context of recent research examining the relationship between working memory (WM) and g.     

A latent variables examination of processing speed, response inhibition, and working memory during typical development

This study addressed three related aims: (a) to replicate and extend previous work regarding the nonunitary nature of processing speed, response inhibition, and working memory during development; (b) to quantify the rate at which processing speed, response inhibition, and working memory develop and the extent to which the development of these latter abilities reflect general changes in processing speed; and (c) to evaluate whether commonly used tasks of processing speed, response inhibition, and working memory are valid and reliable when used with a developmentally diverse group. To address these aims, a latent variables approach was used to analyze data from 147 participants 6-24 years of age. Results showed that processing speed, response inhibition, and working memory were separable abilities and that the extent of this separability was stable across the age range of participants. All three constructs improved as a function of age; however, only the effect of age on working memory remained significant after processing speed was controlled. The psychometric properties of tasks used to assess the constructs were age invariant, thereby validating their use in studies of executive development.     

Linkages Between Children's Social and Academic Competence: A Longitudinal Analysis

The relation between social and academic competence was examined in a group of school-age children (N = 163) using structural equation modeling to determine the direction of influence between these two domains across time. A model posing that a reciprocal relation exists between the two domains was tested. The two nested models within the reciprocal model were also tested. To test these models, social acceptance as well as prosocial and aggressive behaviors were assessed by teachers and peers, and children's academic achievement was measured by language and math report-card grades and work skills. Results supported the reciprocal model, indicating that academic achievement directly influenced social competence from both first to second and second to third grade, and social competence was reciprocally related to academic achievement from second to third grade. Implications of these findings for the education process are discussed.     

Processing speed, intelligence, creativity, and school performance: Testing of causal hypotheses using structural equation models

According to mental speed theory of intelligence, the speed of information processing constitutes an important basis for cognitive abilities. However, the question, how mental speed relates to real world criteria, like school, academic, or job performance, is still unanswered. The aim of the study is to test an indirect speed-factor model in comparison to rivaling models explaining the relationships between different mental abilities and performance. In this speed-factor model, basic cognitive processing is assumed to influence higher mental abilities (IQ and creativity). Intelligence and creativity themselves should be valid predictors of school performance. We computed bivariate correlations and structural equation models to test this hypothesis, using indicators of processing speed [Zahlen-Verbindungs-Test (ZVT) and Coding Test], psychometric intelligence [Kognitiver Fähigkeits-Test (KFT) and Raven's Advanced Progressive Matrices (APM)], creativity [Verbaler Kreativitäts-Test (VKT) and Verwendungs-Test (VWT)] and school performance (grades). In a sample of 271 students from German gymnasiums (Class Levels 9 to 11) the speed-factor model can reproduce at best the empirical relationships between processing speed, intelligence, creativity, and school performance: It assumes that processing speed influences higher mental abilities (intelligence and creativity), which, in the sequel, influence school performance. Therefore, processing speed seems to have no direct effect on school performance; the effect is indirect as it operates via mediation through higher cognitive abilities.