Poverty and brain development during childhood: An approach from cognition and neuroscience

LIPINA, SEBASTIAN J.; COLOMBO, JORGE A.

American Psychological Association

Lugar: Washington, DC; Año: 2009 p. 200

978-1-4338-0445-8

Child poverty and development are complex, multidimensional phenomena, the study of which involves an analysis of different biological and psychosocial components and processes within a continuous, dynamic interaction endowed with a growing complexity. (Bronfenbrenner & Ceci, 1994; Westermann et al., 2007). Both phenomena have been studied by different scientific disciplines that keep debates open on either the universality or context-dependence of biological and psychosocial underlying processes, plus determinants and implications that, still today, embody the most important aspects of the problem at stake. Poverty increases child’s exposure to both biological and psychosocial risks that are most likely to affect developmental and social opportunities. Inasmuch as the strategies that have been implemented worldwide do not appear to have modified significantly the fate of poverty-ridden children, current circumstances challenge the international community to commit themselves in view of the present and future human developments (UNICEF, 2005). Over than one billion children –more than half the child population in African, Asian, Latin American, and Caribbean developing countries- and about 700 million children worldwide are affected by one or more than two forms of severe deprivation, respectively (Gordon, Nandy, Pantazis, Pemberton, & Townsend, 2003). In this context, deprivation refers to inadequate height and weight for age involved, lack of or limited access to drinkable water, and sanitary facilities, no immunization against any diseases, no medical treatment in cases of diarrhea, overcrowding, no kind of education between 7- and 18-year old youth, and no access to either radio, television, telephone, or newspapers at home. Even though this level of severe deprivation does not appear to affect developed countries, child poverty rates in the world’s wealthiest nations vary from under 3% to over 25%. For instance, 47 million children from the nations pertaining to the Organization for Economic Co-operation and Development (OECD) live below their national poverty lines (UNICEF, 2000), and, in the United States of America, 28.6 million children (39%), and 12.7 million children (17%) live in low-income families, and poor families, respectively (Douglas-Hall & Chau, 2007). Mostly, the lack of political and economic considerations to these questions is incomprehensible and disconcerting –unless the possibility is considered that the political and socioeconomic structure is in itself prone to generate such conditions, a sort of intrinsic by-product of its own dynamic, inasmuch as a large body of basic, and practical information aimed at modifying those most preventable risk factors is readily available. As it happens in economic and sociological disciplines too, references to deprivation in current studies dealing with the impact of poverty on child cognitive development mean: lack of income and material resources, basic needs and rights unattended, all of which factors limit the full development of human populations. Such heterogeneity in the sources of variability when considering the concept of deprivation makes it indispensable to adjust poverty conceptual and operational definitions according to each research context, question, and samples. Significantly, in the promotion of this kind of interdisciplinary exchanges, we have to consider child development and poverty as multidimensional phenomena –as stated from the outset, to avoid being inducted to either inappropriate epistemological reductionisms or ethical mistakes. For instance, in the context of Economy and Sociology, only recently child poverty has been conceptually differentiated from poverty in general, such as those experiences of environmental deprivation that results in damages to mental, physical, and emotional development, with significant implications to children rights and basic needs (UNICEF, 2005). Undoubtedly, this conceptual definition stresses the multi-dimensional and interrelated nature of child poverty, besides suggesting that economic safety is only one of its components. However, as several debates are still  exist regarding their causes, and the ways in which poverty in general is likely to be measured, there is no uniform approach to conceptualizing and measuring child poverty (Minujin, Delamonica, Davidziuk, & González, 2006). Despite the fact that the income approach is the most widely used to identifying and measuring poverty in several disciplines, the "income approach" does not include the fact that child’s basic needs are different from adult´s, giving little consideration to household structure, gender, age, or even neglecting well-being dimensions. At the same time, as was addressed by several authors (see for example, Minujin et al. 2006, and Roosa, Deng, Nair, & Lockhart Burrell, 2005),  having access to basic services and protective environments is more dependent on either the level of the developmental context provision or social inclusion than on household income. For example, children are disproportionately affected by those health conditions generated by poor drainage and waste collection, which increase the likelihood of higher rates of preventable injuries and infectious diseases. The same trend was repeatedly verified regarding other factors such as overcrowding conditions and lack of adequate home and school stimulation likely to alter child’s cognitive and emotional development, this with long-term implications (Evans, 2004; Walker et al., 2007). Thus, household income is unlikely to guarantee the satisfaction of basic needs, necessarily. Generally speaking no conceptualization on poverty –"general" poverty as well as child-related poverty at that, includes considerations taking into account children´s specific needs pursuant to their different developmental stages and, this, with regard to either their material needs or their needs for affectionate support. Furthermore, the analysis of impacts of child poverty on the cognitive development varies according to the poverty measurements taken into consideration –in other words, the same effects are not necessarily found in elementary school performance when either income or severe deprivation measurements (Hill & Michael, 2001) are resorted to, on the one hand. On the other hand, different risk factors combinations could be linked to different impact levels on children. For example, low stimulation levels at home, strict parenting styles, and living in overcrowding conditions are high risk factors when it comes to the cognitive performance during the first development years. Nevertheless, not all deprivation combinations, not all privation levels regarding those, or any other factors are likely to generating necessarily a similar impact type and level, and, this, even in the same geographical area or within the same sociocultural group (Guo & Mullan- Harris, 2000). For one thing, this suggests the need to consider current conceptual and methodological advances in the study of child development, including such studies as those recently proposed by Cognitive Neuroscience research (see below), in terms of the identification of which specific, environmental interventions are needed for each specific form of deprivation. Now, this also suggests refraining from applying to a different context, intervention formulas that have been successful within another context. Based on some of these concerns, some international organizations and researchers have begun to see child poverty as a phenomenon that must be defined and measured considering several dimensions of deprivation (Minujin et al., 2006). For instance, the mentioned severe deprivation levels in developing countries belong to a human rights-based approach placing an emphasis on the principles of non-discrimination and equality, and the principle of participation in the decision-making processes. This means adequate nourishment and shelter, opportunity to avoid preventable morbidity and premature mortality, basic education, and the taking part in the community life –that is, social inclusion (Minujin et al., 2006). However, the universal use of poverty indicators still requires a solution at both research and policy levels. Actually, the poverty impact analysis on cognitive performance has been mainly conducted through conceptual definitions based on the income factor, for one thing. On the other hand, a same type of studies in terms of severe deprivation, however, is still missing. Up to now, studies analyzing impacts at the neurocognitive level have only applied variations taken from either income-based or basic needs-based definitions. Thus, although a trend supporting the need to improve child poverty-related conceptualizations and measurement among researchers is on the increase, discussions still exist regarding: a) the range and interpretation of effects, b) the variation thereof in different developmental stages and contexts, c) underlying causal and mediation mechanisms thereof, and d) converting such ideas into government policies. The diversity of poverty effects are also mediated by the co-occurrence and accumulation of different risk factors, present in nearly all development contexts –e.g., home, school, and several community institutions and organizations (Walker et al., 2007). Risk factors refers to those biological and psychosocial hazards likely to  compromise child development at any of the analysis levels –e.g., intrauterine growth restrictions, undernutrition, specific nutritional deficits, infectious diseases, environmental toxic exposures, parental home stimulation, sensitivity and responsivity. A majority of these risks could be prevented through appropriate policies, so the reduced views on child poverty and development increase the likelihood of not changing children opportunities. Thus, a multidimensional view on poverty and development is also important a fact for the designing of interventions at multiple levels to adequately evaluate their impacts as well as allowing an appropriate planning of financial, material, and human resources to adjust and improve actions. We had to wait for more than forty years, devoted to research based on intervention and educational programs for children living in poverty, before watching that specific, conceptual, and methodological recommendations were at least proposed (Ramey & Ramey, 2003). Evaluations of these programs have been associated to the impact of a wide set of intensive and high-quality services, including cognitive training and education, plus environmental maintenance thereof by means of parents´, teachers´ and other caregiver’s involvement. Those projects, using appropriate designs with adequate controls, as well as conceptual and methodological frameworks based on complex and ecological approaches, have produced the best effects. However, not all children benefit in the same way from their participation in this type of programs. Individual differences are due fundamentally to multiple, interactive factors, among which the early status of children in terms of their biological inheritance and risk accumulation, as well as variations in the development context quality are crucial (NICHD, 2005; Ramey and Ramey, 1998). Within this analysis context, the recent findings on how children´s genotypic nature modulates children´s cognitive performance –after a specific training of their attention networks, constitute a promising research trend into the intervention area (Rueda, Rothbart, McCandliss, Saccomanno, & Posner, 2005). Hence, appropriate experimental designs shall allow alternative approaches to be explored, further contributing to the design and adjustments of the same or other interventions and public policies. This means that both basic and applied research works continue being crucial not only for a more in-depth knowledge about poverty impacts on several developmental areas, but also to design actions aimed at situations improvement and optimization. In this sense, it should be noted that scientific contributions are not expected to replace any social and political objectives against poverty: they are expected to inform us about it. Particularly, this book is intended to contribute to this field of study by incorporating several conceptual and methodological approaches, developed in the context of different neuroscientific disciplines, such as Developmental Cognitive Neuroscience and Cognitive Psychology, based on proven experimental and applied methodologies, aimed at analyzing poverty impacts as well as cognitive optimization through interventions. In the last four decades, several experimental projects and programs have contributed to significant advances in the understanding of how material and social deprivation impacts on brain organization and development at different analysis levels, from the molecular up to the learning processes levels. These advances form part of wealth of contributions in a broad body of basic as well as applied knowledge. Especifically, the study of early cognitive development involves the consideration of several components and processes taking place at different times and at various analysis levels. Hence, environmental deprivation factors could either modify or alter child’s cognitive development inasmuch as changes in some of those interrelated and interdependent subsystems components or processes are likely to affect the ongoing developmental process. Such an impact could vary according to the amount and timing of deprivation, as well as the individual susceptibility, quality and cultural nature of developmental contexts (NICHD, 2003, 2005). In turn, as mentioned, the concept of deprivation varies depending on different scientific disciplines. In the context of neuroscientific experimental animal models, environmental deprivation refers specifically to the controlled manipulation of different material and social conditions in laboratory animals, aimed at modulating several inputs (Grossman et al., 2003; Mohammed et al, 2002). Of course, controlling these conditions as well as using animal models –the only experimental alternative to analyze the most elementary levels of brain components and processes such as molecules, dendrites, or synapses–, limits the possibilities to extrapolate findings for the analysis of human contexts. However, they allow an understanding on basic, neural underlying processes at molecular and cell levels to be achieved. Besides, these studies allow us to analyze in which way specific deprivations are linked, or not, to impacts that are also specific, such as a modulation of social deprivation vs. material deprivation, or a combination thereof on different, molecular or cell components of the brain cortex (Markham, & Greenough, 2004). With regard to impact caused, as already mentioned, there exists an agreement about the fact that poverty involves multiple alterations and impacts on physical growth, cognitive, and socioemotional development. Especifically, as regards brain development and function, recent studies show that poverty affects people from birth to adulthood. For example, the 2003 and 2005 studies performed by both the National Institute of Child Health and Human Development (NICHD) and the Early Child Care Research Network have shown that the quality of home environment predicted child’s performance in sustaining attention, memory, and inhibitory control tasks. These types of studies address the need to evaluate the role of different dimensions and mediators through which the environment may influence those and other basic, cognitive processes involved in school and social functioning (Noble, McCandliss & Farah, 2007). In this sense, recent behavioral studies carried out in different countries, have showed the impact of pertaining to a socially disadvantaged home, this when it comes to subjects´ cognitive performance in tasks requiring basic operations related to different brain networks specific activation. For instance, Mezzacappa (2004) has verified a pattern of associations between children´s basic cognitive functions of attention, and their socioeconomic status –e.g., socially disadvantaged children performed less proficiently under all ANT conditions. Lipina and colleagues (2004, 2005) found that infants and preschoolers from socially disadvantaged homes performed less proficiently in different tasks requiring monitoring and control operations, such as working memory, inhibitory control, attention, flexibility, and planning. Blair & Razza (2007) have examined the role of self-regulation in emerging learning abilities among preschoolers from low-income homes, showing that although children’s self-regulatory competences –executive function, effortful control, and false belief understanding, were moderately correlated, each of these constructs also tended to account for an unique variance in mathematics and literacy measurements with regard to measuring the very first steps in calculation and  reading-and-writing activities. In a recent series of studies Noble, Farah, McCandliss and colleagues have assessed, from a behavioral perspective, several neurocognitive systems of preschool children, schoolchildren, and preadolescents, to determining socioeconomic contributions with regard to performance and neural activation (Farah et al., 2006; Noble, Norman, & Farah, 2005a; Noble, Farah, & McCandliss, 2006a; Noble et al., 2007; Noble, Wolmetz, Ochs, Farah, & McCandliss, 2006b). Summing up, findings have shown  that socioeconomic background differences were associated with disparities in language performance and executive function systems as well, suggesting that language and executive systems are very susceptible to environmental influences. In addition, the last mentioned studies also coincide with others that specifically show influences of parenting (Landry, Millar-Loncar, Smith, & Swank, 2002), and parents´ educational level (Ardilla, Rosselli, Matute, & Guajardo, 2005) on the development of the executive functions of children from different cultures, as well as the socioeconomic modulation of maternal speech on early vocabulary development (Hoff, 2003). Finally, in perhaps the first developmental imaging study applied to the analysis of poverty impacts on brain function, Noble and colleagues (2007) have studied how socioeconomic status modulated children brain activity during reading practices. Especifically, using a functional magnetic resonance imaging (fMRI) allowing co-evaluating brain activation and cognitive performance, these authors have shown a significant phonological awareness and socioeconomic status interaction in the activation of the left fusiform area –a brain area related to reading processing, even after controlling influential covariates. The implemented approach has opened a promissory way of analysis since activation represents a crucial dimension in terms of the characterization and development of basic cognitive processes, and the possibilities to modify them by exercising, training, or education. Recently, a growing interest has been observed regarding the potential contributions of Cognitive Neuroscience to education, and learning (Ansari & Coch, 2006; Goswami, 2006; Posner & Rothbart, 2005, 2007b), and also in the field of intervention oriented to improve disadvantaged children´ cognitive and psychosocial performance. Such an interest is based on results from different laboratory studies on behavioral training, and remediation of basic cognitive processes in healthy, as well as sick children. For example, Rueda and colleagues (2005) have designed and applied an executive attention-training program for 4- and 6-year old healthy children. Authors showed that trained groups obtained a more mature performance in the Attentional Networking Test (ANT), a generalization effect on an intelligence test (K-ABC), and changes in the pattern of brain activations within areas related with the demanded cognitive operations using event-related potentials (ERPs). Also, with regard to an examination of differences in temperament and genotype, said authors have found that a specific allele (long form) of the DAT1 dopamine gene transporter was associated with a stronger effortful control and less extraversion scores, suggesting that less outgoing, more controlled children may require less attention training. That study showed both genotype and training influence performance on attentional and intelligence specific tasks in 4- and 6-year old healthy children.  Klingberg and colleagues (2002, 2006) have designed a working memory training paradigm, and then evaluated its effect in school-age children and adolescents with attention deficit and hyperactivity disorder (ADHD). Results have showed that intensive, adaptive computerized working memory training gradually increased the amount of information that children could maintain on line. McCandliss and colleagues (2003) have examined the reading skills of school-age children with deficient decoding skills, before and after an intervention in the context of a controlled randomized design. Findings indicated that participation in the program resulted in gains in decoding, phonemic awareness, and passage comprehension skills. Shaywitz and colleagues (2004), and Temple and colleagues have designed and applied a phonologically mediated reading intervention combining behavioral and imaging approaches which showed that children participating in the intervention protocol made more significant gains in reading and fluency skills than children in control groups. Moreover, increased activation in related brain areas proved to be associated with behavioral gains. Finally, Wilson and colleagues (2006) have designed an adaptive, computerized game for the dyscalculia remediation, inspired by Cognitive Neuroscience research works especifically conducted on the current understanding of brain representation of numbers. Results have suggested that an application of this software was successful in increasing a "sense for numbers" over a short study period. The application of Cognitive Neuroscience frameworks to either intervention programs or educational curriculums, aimed at improving socially disadvantaged children’s cognitive development, are even more preliminary than the studies we have just described. Currently, approaches by McCandliss and colleagues (2003), and Wilson and colleagues (2006a), are being applied in New York schools (McCandliss, in preparation), and Europe schools as well (http://www.unicog.org). Based on previous studies, Colombo, Lipina and colleagues (Colombo & Lipina, 2005) have designed and applied a controlled, randomized, multimodular intervention program including cognitive exercise, nutritional supplementation, teacher training, health and social counseling for parents, to be applied to a sample of healthy, 3- to 5-year old children from disadvantaged homes. Results showed that participating in a 32-session arrangement a year, combined with an iron and folic acid supplementation was an effective mean to improve both the working control and the monitoring processing in the intervention groups. Finally, the Tools of the Mind curriculum has proved that it improved executive functions in a disadvantaged preschool sample from low-income urban schools (Diamond, Barnett, Thomas, & Munro, 2007). So, the Cognitive Neuroscience studies herein described have been useful to identify effects of poverty on specific basic cognitive processes, strongly associated with the early development of crucial literacy and numeracy competences from kindergarten onward, and also on temperament individual differences. The same processes have been subject to the design and implementation of either intervention programs or trials, the results of which, with different child populations, encourage researchers to transfer those programs to the poverty field of study, as conceptual and methodological approaches and actions. Obviously there is a need to enhance the comprehension on the effective contents and procedures aimed at: a) achieving generalized improvements; b) how long does it take for interventions to succeed in altering affective networks; and c) how widely will they generalize –however, the Cognitive Neuroscience current findings may help scientists and policy makers to improve their approaches aimed at optimizing the quality of life of disadvantaged children. More especifically, the purpose of the present volume lies in reviewing the impact of different types of early deprivations on the structural and functional brain organization; describing how poverty impacts on the cognitive and socioemotional development, and then analyzing the potential contributions of neuroscientific disciplines to the design of early interventions aimed at optimizing the cognitive performance of socioeconomic disadvantaged children. In this regard, authors expect this book to represent a contribution to deepen debates, and useful for students and colleagues interested on this extremely sensible field. Taking these objectives into consideration, the book is organized in the following six chapters: Chapter 1 proceeds to a close review on the conceptual and operational poverty definition issue, focusing on currently available child indicators, policies and research implications. Chapter 2 reviews the effects of material and social deprivation on molecular, cell, and network systems levels of brain functioning and organizations. This analysis focuses on results obtained from studies on rodents and primates. Discussions are included on brain plasticity, critical periods, and brain modification achieved by learning experiences as well as specific skill training. These issues are considered to be relevant to the understanding of the different analysis levels of cognitive and socioemotional development. Chapter 3 describes the effects of poverty on physical and mental health, and their underlying mechanisms in the context of a multidimensional risk factors analysis. This Chapter also includes a review of studies on children’s cognitive performance, pursuant to different theoretical frameworks -e.g., psychometric, socio-cultural and developmental psychology frameworks differing, from Neuroscience and Cognitive Psychology approaches-. Also, “socially-generated experiments” including children are presented –e.g., orphans. Chapter 4 includes and analyzes the current results of poverty impact on brain functioning in the context of studies with human populations. The differentiation between Neuroscience and other perspectives as described in the preceding chapter –such as psychometry for example, is based on epistemological differences regarding cognitive operations as constructs, and, consequently, which is the best way to both construing and applying cognitive performance–. Current behavioral and neuroimaging experiments are analyzed, with a special emphasis placed on methodological and technical issues. Chapter 5 describes and analyzes current examples of intervention programs or modules, aimed at modifying the brain activation patterns and/or the cognitive performance of healthy children –with and without socioeconomic disadvantaged backgrounds, as well as children affected by either ADHD, or dyslexic and dyscalculic disorders. The cognitive performance of children living in poverty is examined from neuroscientific and cognitive frameworks based on experiments that have been carried out in different countries. Advantages of and differences from other intervention programs are discussed. Finally, Chapter 6 presents several issues linked to the contributions of Cognitive Neuroscience and Cognitive Psychology to public policies for disadvantaged children, including a discussion on technological and ethical concerns. In addition, brief and specific recommendations to officers and educators working with disadvantaged children are included.