Resumo Reserva cognitiva é a habilidade em otimizar o desempenho através do recrutamento de redes neurais, que talvez reflitam o uso de estratégias cognitivas alternativas. Objetivos: Identificar fatores relacionados à reserva cognitiva associados à progressão do comprometimento cognitivo leve (CCL) para demência degenerativa. Métodos: Uma coorte de 239 indivíduos com CCL (idade: 72.2±8.1 anos, 58% mulheres, educação: 12 anos) foram avaliados e seguidos por cinco anos (2001-2006). Resultados: No primeiro ano 13.7% dos CCL converteram para demência e 34.7% em três anos (78.3% converteram para doença de Alzheimer). Os fatores de risco para aqueles que converteram foram: educação menor do que 12 anos, MMSE menor do que 27, teste de Nomeação de Boston menor do que 51, QI (Quociente de Inteligência) menor do que 111, idade superior a 75 anos, falta de ocupação na aposentadoria, e presença de intrusões na memória de evocação (todos contando para 56% da variabilidade de conversão). Conclusões: Pacientes com CCL são uma população de risco para demência. O estudo dos fatores de risco (como QI, educação e ocupação), principalmente, aqueles relacionados à reserva cognitiva podem contribuir para uma evidência importante para o processo de decisões na atividade clínica e na saúde pública.

Abstract Cognitive reserve is the ability to optimize performance through differential recruitment of brain networks, which may reflect the use of alternative cognitive strategies. Objectives: To identify factors related to cognitive reserve associated with progression from mild cognitive impairment (MCI) to degenerative dementia. Methods: A cohort of 239 subjects with MCI (age: 72.2±8.1 years, 58% women, education: 12 years) was assessed and followed for five years (2001 to 2006). Results: In the first year, 13.7% of MCI converted to dementia and 34.7% converted within three years (78.3% converted to Alzheimer's dementia). Risk factors for those who converted were education less than 12 years, MMSE score less than 27, Boston naming test score less than 51, IQ (Intelligence Quotient) less than 111, age over 75 years, lack of occupation at retirement, and presence of intrusions in memory recall (all account for 56% of the variability of conversion). Conclusions: MCI patients are a population at high risk for dementia. The study of risk factors (e.g. IQ, education and occupation), particularly those related to cognitive reserve, can contribute important evidence to guide the decision-making process in routine clinical activity and public health policy.

In general, the effects of poverty on early cognitive performance have been studied using a definition of poverty based on terms of income, and within the context of paradigms of cognitive evaluation based on the hypothesis of a general intelligence factor. Conversely, in the present report the concept of Unsatisfied Basic Needs (UBN) was used as poverty criterion, and a cognitive paradigm of executive functions based on neurobiological concepts was applied. This paradigm outlines the existence of discrete and interactive components of cognitive functioning guided toward objectives, and associated to the activation of cerebral circuits that involves the prefrontal cortex. The performance of 247 preschoolers (3 to 5 year-olds) from schools in District 4 of the City of Buenos Aires (Boca-Barracas), and in the districts of Vicente López and San Isidro of Gran Buenos Aires, was compared. Sample groups included children from poor (UBN) and non-poor homes or with Satisfied Basic Needs (SBN). They were studied with a battery of executive tests [A-not-B, Spatial Reversal, and Color Reversal (Espy, Kaufmann, McDiarmid, & Glisky, 1999); Three and Four Colors (Balamore & Wozniak, 1984); Strooplike Day-Night (Gerstadt, Hong, & Diamond (1994); and Tower of London (Shallice, 1982)] to evaluate the components of cognitive flexibility (working memory, attentional shifting, self-monitoring, and conceptual transfer), goal-setting (initiating, planning, problem solving, and strategic behavior), and attentional control. A selection procedure was applied to all cases, taking into account: prematurity, weight at the time of birth, medical record of neurological and developmental disorders, actual weight, height and their relationship at the time of testing, intellectual quotient of execution (WPPSI), and official certification of child abuse in their homes. Poor homes were identified by applying a scale of socio-economic level (NES) based on conceptual and operational definitions used by the Instituto Nacional de Estadísticas y Censos (INDEC) of Argentina. Bivariate and multivariate tests were applied to analyze the effects of the independent variables (socio-economic group, age, sex and difficulty level) on the dependents and their interactions. Correlations and simple regressions were applied to analyze the associations between cognitive performance and socio-economic level. In A-not-B, Spatial Reversal and Color Reversal tests the UBN group made less previous correct trials before reaching the efficiency criteria (difficulty to find the hidden rule) and consecutive correct trials (difficulty to maintain outstanding information). They also made more reiterative errors (failure in the control of interferences). In the Three and Four Colors Test, the UBN group had lower scores in all the analyzed variables. Children within this group also needed more demonstrations and verbalizations from the experimenters. In the Tower of London Test, UBN children showed an increased delay to begin and to organize the task, and were less efficient in achieving the objectives. Planning time decreased when cognitive demands were increased. The SBN group showed an inverse profile. Both groups had similar performance in the Stroop-like Day-Night Test. When performance variations were analyzed in terms of age and difficulty level, the tendencies were similar to those reported in previous studies. Gender differences were registered in A-not-B and Tower of London tests, with girls showing a better perform-ance. Finally, there were positive associations between performance success and socio-economic total score, and negative associations between errors and socio-economic total score. Present results confirm that poverty has a negative impact on cognitive performance in terms of the executive function paradigm used. The advantages of a cognitive paradigm based on a neurobiological theoretical framework in the context of social and school intervention programs for children from a socially risky population, are also discussed.

El estudio de los efectos de la pobreza sobre el desempeño cognitivo durante las primeras fases del desarrollo, ha sido efectuado predominantemente en base a la definición de pobreza según el ingreso y el uso de paradigmas de inteligencia basados en la hipótesis de un factor general de funcionamiento cognitivo. En el presente trabajo se utilizó el concepto de Necesidades Básicas Insatisfechas (NBI) como criterio de pobreza y se aplicó un paradigma cognitivo de funcionamiento ejecutivo proveniente de la Neurociencia. El mismo plantea el análisis de componentes de comportamientos inteligentes orientados hacia objetivos y asociados a la activación de circuitos cerebrales que involucran centralmente a la región prefrontal. Se comparó el desempeño ejecutivo de 247 niños escolarizados de 3 a 5 años de edad, provenientes de hogares pobres (NBI) y no pobres o con Necesidades Básicas Satisfechas (NBS), y de jardines de infantes del Distrito Escolar 4 de la Ciudad de Buenos Aires (Boca-Barracas) y de distritos escolares de Vicente López y San Isidro del Gran Buenos Aires (Argentina). Se administró una batería de pruebas que evalúan componentes de flexibilidad cognitiva, logro de objetivos y control atencional. Los resultados obtenidos muestran perfiles de desempeño diferentes entre ambos grupos. El perfil de desempeño menos eficiente en términos de las variables estudiadas se observó en el grupo de niños proveniente de hogares pobres. Estos resultados constituyen un aporte significativo de un paradigma neurocientífico para la implementación de estrategias de intervención orientadas a estimular el funcionamiento cognitivo de tipo ejecutivo de niños de edad preescolar.