In 2007 it was reported that an estimated 33 million people worldwide were living with the Human Immunodeficiency Virus (HIV). Of this, 35% (approximately 11.5 million) live in South Africa, most of whom were infected with HIV by mother to child transmission. Due to government legislation, until 2004, South Africans had limited access to Antiretroviral (ARV) treatment at and after birth. As a consequence, treatment of HIV was, at this time, only in government facilities, initiated after the clinical presentation of immune deficiency. This study compared the memory functioning of low socio-economic seropositive adolescents that were on a managed anti-retroviral programme to that of a contrast group that were HIV negative. The groups were matched for age, gender, demographics and educational level. The relative impact of variables such as duration of ARV treatment, drug regimen, WHO stage at diagnosis and CD4+ count were all considered. Performance on a comprehensive neuropsychological battery was compared between the HIV positive group and their typically developing counterparts both in terms of memory functions as well as other cognitive processes that may have an effect on memory. The HIV positive group performed significantly below their HIV negative peers in processing speed, holistic processing, and spatial processing as well as specific visual functions such as visual constructional skills, visual recall ability, disruptions in both storage and retrieval of visuospatial information, and visual spatial working memory. No significant differences were found between the groups on tasks measuring verbal memory and verbal learning ability indicating that the neurocognitive profile of clade C HIV has a different presentation from the other clades. The findings suggest that the preferential effect HIV has on the frontostriatal circuits in the brain impacts memory processes due to the destructive impact of the virus on the myelination of these circuits. As a result of the higher degree of white matter tracts in the right hemisphere, holistic and integrative processing is impaired and visuospatial functions are affected whereas verbal processes are largely spared. The resulting neurocognitive profile is similar to that of nonverbal learning disorders and may benefit from similarly constructed interventions such as placing more emphasis on verbal learning strategies and limiting dependence on visual information for HIV positive pupils.

No presente trabalho é apresentado o Teste de Omissões Voluntárias (Square-Skipping Test, SST), uma versão de papel e lápis da tarefa computadorizada do sinal inibitório. Na primeira parte do trabalho, são relatados estudos que utilizaram uma tarefa computadorizada do sinal inibitório com estímulos excitatórios e inibitórios apresentados visualmente em um procedimento lateralizado. As estratégias de esperar o sinal inibitório foram controladas com sucesso mediante o controle "on-line" da estabilidade dos tempos de reação ao sinal excitatório. Um dos objetivos foi elucidar algum possível fator comum subjacente ao desempenho na tarefa do sinal inibitório e no Teste da tarefa Dupla. Os tempos de reação ao sinal inibitório não foram afetados pela lateralização, enquanto que os tempos de reação ao sinal excitatório direito foram os mais rápidos. Esta vantagem, a qual parece envolver especialização hemisférica e comunicação interhemisférica, correlacionou com a perda no desempenho da tarefa de box-crossing quando combinada com a tarefa verbal no Teste da Tarefa Dupla. A diferença Parte B-menos-Parte A do Trail Making Test correlacionou com os tempos de reação simples. Os resultados também sugerem a associação entre o tempo de reação simples e funções executivas. Foi descartada uma assimetria no sentido do deslocamento da atenção entre hemicampos para explicar a vantagem dos tempos de reação ao sinal excitatório direito. O tempo de reação simples parece ser uma medida de capacidade executiva. A comparação do desempenho de adultos idosos e jovens, medido pela tarefa computadorizada, demostrou que o controle inibitório não foi afetado de forma significativa pela idade. Na segunda parte do trabalho, é apresentado o SST, o qual permite obter de forma prática e rápida, medidas da habilidade inibitória e outras capacidades executivas tais como a flexibilidade cognitiva, a atenção concentrada e a velocidade na busca visual. O SST foi validado mediante a comparação com o desempenho na tarefa computadorizada do sinal inibitório. A execução do SST requer marcar com ‘Xs’ quadradinhos alinhados em um caminho irregular impressos em uma folha A4 (Parte D), sendo que nas Partes A, B e C devem-se omitir alguns quadradinhos indicados. Na terceira tentativa do SST deve ser escrita a seqüência de dígitos ‘1, 2, 3’. A correlação com o teste computadorizado do sinal inibitório sugeriu que o controle inibitório seria medido pela Parte D preenchida com a seqüência de dígitos (Parte D3). A idade não afetou de forma significativa o desempenho na Parte D3. O fator idade parece afetar seletivamente o desempenho nas diferentes partes do SST; p. ex. na Parte A1, que correlacionou com o coeficiente de atenção concentrada do Teste de Toulouse-Pièron. Para evitar os efeitos da prática sobre o desempenho no SST, recomenda-se a execução do Teste da Tarefa Dupla antes da execução do SST, e de preferência na mesma sessão experimental. / The present study aims to contribute to the understanding of the inhibitory ability, within the framework of the neuropsychology. The objective was to develop a paper-and-pencil test to assess the ability to stop an action in a simple and rapid way. A computerized stop signal task was used to validate the test. In the first part of this work, studies that involved the computerized stop signal task are presented. The result of these studies allowed to raise some theoretical issues. The paper-and-pencil test is presented in the second part of this work. In the Experiment 1 the aim was to control experimentally the strategy of waiting for the stop-signal on a lateralized stop signal task, by means of an algorithm, which controlled, on-line, the variation of response latencies for the go-signal (GSRT). Thirty-four healthy volunteers participated in this study. The GRST of the group that performed the task without the algorithm were significantly higher than the GSRT of the group that performed the task with the algorithm, whereas the stop-signal reaction times did not reach significant differences between groups. This procedure provided more stable reaction times throughout the task, and shifted the probability of responding on stop-trials from 0.364 to 0.479. The Experiment 2 studied the relationship between reaction time, laterality, and executive functions were examined by employing two computerized tasks with lateralized visual stimuli. Simple reaction time (SRT) was correlated with the Part B-minus-A difference of Trail Making Test (TMT). No significant difference was found between left and right SRT. Reaction times for left go-signals of the Stop-task were longer than reaction times for right go-signals. The ratio of left go-signal-minus left SRT to right go-signal-minus-right SRT was correlated with the loss in the visuospatial component when it was combined with a concurrent verbal task in the Dual-Task Test. Results suggest association between SRT and executive functions, and the involvement of hemispheric specialization and interhemispheric transfer in both, the stop signal task and the Dual-Tasks Test. Results from Experiment 3 permit to discard the possibility that the observed right visual field advantage observed was due to the orienting of attention across hemifields. The left GSRT were significantly slower than right GSRT. The right GRST advantage was not due to an attentional shift between left and right visual hemifields. In the Experiment 4, the stopping ability of older people in the computerized stop task was explored. There were no significant differences between the stopping ability of older and younger adults. The Square-skipping Test (SST) a paper-an-pencil version of the stop signal computerized task. is described in the second part of this study. The SST is divided in four parts. The effect of the administration of the different parts of the SST was studied in Experiment 5. The results allow for the use of the four parts in the same trial, since there was no effect of order of administration. In Experiment 6 it was studied the effect of placing a digit sequence on the third trial of the test, instead of the X’s. It seems that a greater degree on the inhibitory ability is necessary to perform the task with the sequence "1, 2, 3", than with the sequence "3, 2, 1". Thus, the sequence "1, 2, 3" was used in the final version of the SST. The practice effects of the Dual-Task Test on the SST was studied in Experiment 7. The interaction Group x Trial showed a general decrease on the performance of participants without previous practice in the Dual-task Test, contrasting with the performance of participants with within-session practice, which showed a clear digit sequence load effect. The aim of Experiment 8 was to know possible aging effects in the performance of SST. A general decrease was observed in the performance of older adults compared with performance of young adults; the interaction Group x Trial showed that the slope of the curves were different. The performance in SST is significantly affected by age. Performance in SST correlated with performance in the stop signal and the SRT tasks, respectively. Performance in SST also correlates with TMT, with the visuospatial component of the mu index of the Dual-task and with the attention coefficient of the Toulouse-Pièron Test. The best predictor of the stopping ability was the performance on the Part D with the digit sequence (Part D3). Thus, SST seems to be a useful neuropsychological tool for the assessment of several executive functions, including the stopping ability, mental flexibility, speed for visual search and focused attention.

Damage to the ventromedial prefrontal cortex (vmPFC) can lead to disturbances in personality, emotional dysregulation, impairments in social conduct, and difficulties in decision-making. Many researchers have likened the conduct of individuals with vmPFC lesions to that of criminal psychopaths, labeling the effects of vmPFC damage “pseudopsychopathy” or “acquired sociopathy.” However, although psychopathy—a condition marked by a distinct mosaic of antisocial personality traits and behaviors—has been studied and characterized as a psychological and behavioral disorder by many researchers, the overlap between acquired sociopathy and psychopathy remains ambiguous. This study assessed the severity of psychopathic personality traits in neurological patients with acquired damage to the vmPFC using both informant-report and self-report measures. On both informant-report and self-report measures, individuals with vmPFC damage showed no significant elevations across a wide range of psychopathic traits relative to demographically-matched neurologically healthy comparison participants and patients with damage outside of the vmPFC. The results showed only one trait, Fearlessness, that was significantly higher in patients with vmPFC lesions relative to the neurologically-healthy comparison group.

En este estudio convergen conocimientos de neuropsicología y tecnologías de la información para el desarrollo de una aplicación informática que optimice una batería de identificación de disfunciones cognitivas en pacientes adultos con esclerosis múltiple. Esta aplicación informática es presentada como respuesta a una clara necesidad de los centros médicos especializados en neurología de proveer herramientas que permitan la inclusión del mayor número de pacientes con esclerosis múltiple a la administración de baterías de identificación de disfunciones cognitivas. El desarrollo de un sistema informático que contenga y permita rendir las pruebas que conforman la batería, la posterior calificación de las mismas, la interpretación de los resultados, el almacenamiento y la actualización de la historia clínica del paciente conforman la sistematización de la batería de identificación de disfunciones cognitivas brindando beneficios reales al segmento en estudio manteniendo la eficacia de la administración. Además, se espera crear un precedente de la adherencia de los pacientes frente a la solución informática propuesta con el fin de ser base favorable para futuras soluciones informáticas que decidan incursionar en temas médicos. Con la meta de cumplir adecuadamente el desarrollo de la aplicación informática basada en el conocimiento, el presente documento ha sido estructurado en ocho capítulos: 1) fundamentos teóricos del negocio, las tendencias y tecnologías actuales, el objeto de estudio, el campo de acción y el análisis crítico de los problemas de información; 2) propuesta de solución indicando los objetivos y beneficios del proyecto; 3). modelado del negocio bajo la metodología del Proceso Unificado de Rational; 4) requerimientos y modelado de la aplicación informática; 5) arquitectura de software; 6) construcción del sistema; 7) muestra la calidad y pruebas del producto; y 8) la gestión del proyecto. / In this study, knowledge of neuropsychology and information technologies converge for the development of a computer application that optimizes a battery of identification of cognitive dysfunctions in adult patients with multiple sclerosis. This computer application is presented as a response to a clear need of medical centers specialized in neurology, to provide tools that allow the inclusion of a largest number of patients with multiple sclerosis in the administration of batteries of identification of cognitive dysfunctions. The development of a computer system which contains and allows perform the tests that conform the battery, the subsequent qualification of the same tests, the interpretation of the results, the storage and the updating of the patient's clinical history make up the systematization of the battery of identification of cognitive dysfunctions providing real benefits to the segment under study maintaining the effectiveness of the administration. In addition, it is expected to create a precedent for the adherence of patients to the proposed computer solution in order to be a favorable basis for future IT solutions that decide to explore medical issues. Considering the goal of fulfilling the development of the knowledge-based computer application properly, this document has been structured in eight chapters: 1) theoretical foundations of the business, current trends and technologies, the object of study, the field of action and the critical analysis of information problems; 2) proposed solution indicating the objectives and benefits of the project; 3). modeling the business under the Rational Unified Process methodology; 4) requirements and model of the computer application; 5) software architecture; 6) system construction; 7) shows the quality and testing of the product; and 8) project management. / Tesis

Neuropsychological tests are standardized tasks used to measure psychological functioning that is associated with a particular brain structure. These tests often are used in diagnosing a cognitive deficiency resulting from brain injuries. Currently, there are a limited number of studies that have focused on standardization of neuropsychological tests in Latin America. Therefore, the vast majority of cognitive tests used in the evaluation of patients with brain damage have no normative parameters adjusted to the cultural characteristics of Latinos and Latinas. As a result, neuropsychological diagnoses among this population may be inadequate, and evaluation of rehabilitation program effectiveness limited. The importance of culturally appropriate indices of neurological tests cannot be overstated; of all the problems presented by individuals with brain injuries, cognitive disorders are the leading source of disability for adequate work, family, and social reintegration among this group. There is an urgent need to standardize neuropsychological tests in Latin America, among Latinos in the US and any other regions where neuropsychological test have not been standardized. An important population subgroup in Latin America severely lacking in norms for many neuropsychological tests are those deemed illiterate or unable to read or write. Developing normative data for individuals who are illiterate will allow neuropsychologists to have a more accurate comparison when attempting to diagnose cognitive deficits among this group in Latin America. This dissertation is unique, as no other studies have looked at the normative data and standardization of neuropsychological tests within this population in Latin America.

Decision-making in the context of leadership, has received scant attention in the management literature, which has traditionally centered on general mental ability and personality as predictors of effectiveness. This research effort bridges the neuroscientific and management literatures to offer an alternative, neuropsychological profile of effective leadership by proposing prefrontal brain processes (executive function) as a key component and predictor of complex decision-making and leadership effectiveness. While the management literature has largely viewed decision-making as a cognitive ability, neuroscience informs us that this complex function emerges from the integration of affective and cognitive signals in the prefrontal cortex. In an attempt to identify the neural predictors of effective leadership decision-making, 105 corporate leaders were assessed on a robust array of neuropsychological indices of prefrontal brain function. These were in turn correlated with their leadership and decision-making abilities after controlling for general mental ability and personality, utilizing structural equation modeling. Executive function incrementally predicts complex decision-making and transformational leadership effectiveness, above and beyond general mental ability. Complex decision-making does not appear to be central to leadership effectiveness, while extraversion emerges as the strongest predictor of transformational leadership followed by executive function. Executive function, extraversion and general mental ability do not predict transactional leadership. These results would need replication in a larger dataset to establish their validity, especially in the case of executive function. While the heritability of leadership ability has emerged as fairly significant, this opens the field to unearthing the biological variables and predictors of leadership ability. Neuroscience thus has the potential to offer biomarkers and metrics of leadership that can further not only our foundational knowledge of organizational behavior, but can also find useful applications in recruitment, training and development practice, though this cross-disciplinary initiative is in its infancy. Based on the preliminary results from this study, executive function (which has so far remained in the domain of neurology) has the potential to inform and measure leadership effectiveness.

According to the theory of cognitive reserve, cognitively enriching aspects of life experience (e.g., education, occupation, and leisure activity) foster the development of more efficient neural networks and cognitive strategies, enabling individuals to cope more effectively with the pathology of dementia. Using extant data from a population-based study, we examined: (1) the effect of reserve accrued through middle life on course of neuropsychological decline; and (2) the role of ongoing engagement in mentally stimulating leisure activities in rate of general cognitive and functional deterioration. In linear mixed models, level of occupational attainment did not affect rate of cognitive or functional decline, although women were found to undergo more rapid deterioration in cognitive ability. Occupational skill area was associated with trajectory of decline in several neuropsychological domains. Specifically, vocations emphasizing practical, hands-on skills were associated with slower deterioration in auditory-verbal and visual memory, as well as visuospatial and constructional abilities. Teaching and helping professions, in contrast, were associated with more rapid decline in memory and executive functioning. Increased engagement in cognitive leisure activities through late life was associated with slower deterioration in general cognitive ability in mild dementia, but its effects were no longer evident in more severe AD. An understanding of how rate of decline intersects with patients' past histories and efforts to maintain and enhance cognitive capacity will enable clinicians to target areas for cognitive training and rehabilitative therapy.

Objective: The purpose of this study was to assess the influence of three single nucleotide polymorphisms (SNP) previously associated with Alzheimer's disease on specific domains of cognition, when controlling for Apolipoprotein E gene (APOE), in a sample of individuals with Alzheimer's disease. Methods: The data were drawn from the Alzheimer's Disease Neuroimaging Initiative database, a comprehensive, longitudinal database of controls, persons with mild cognitive impairment, and persons with mild Alzheimer's disease. Each subject has a full neuropsychological assessment, neuroimaging, genetic sequencing, and physical evaluation. For the purposes of this study, individuals were selected based on the presence of the three SNPs of interest: CR1 (rs3818361_T), CLU (rs11136000_T), and PICALM (rs3851179_A). Each SNP was then measured against the available tests of the ADNI neuropsychological battery that measured immediate and long delay memory, semantic fluency, and confrontation naming. Results: Only the CR1 SNP (rs3818361_T) had significant findings. The presence of the CR1 SNP associated with lower performance on logical memory recall total score, AVLT immediate recall trials 2 and 4, AVLT delayed recall, and confrontation naming in the 12-month control group. Logical memory and AVLT delayed recall were also negatively associated with CR1 in the 12-month AD case group. Discussion: These results support previous findings that the CR1 SNP rs3818361_T is a risk factor for cognitive impairment in individuals with and without AD. Such findings can aid in the earlier detection of Alzheimer's disease, risk for domain specific cognitive impairment, and novel targets for personalized pharmacotherapy.

Using a multimethod-multimodal approach, this study compared the contributions of executive function (EF) abilities (Go No-Go, Visual Search, 2-Back task, and Task Switching) to narrative comprehension tasks (False Belief, Strange Stories, Self-Reported Theory of Mind Inventory [TOMI-SR]) and a narrative production task (interpersonal decentering) in a sample of young adults. Separate regression models were conducted for each theory of mind (ToM) measure with EF measures as predictor variables and empirically selected demographic variables controlled. As expected, in this college student sample (N = 110), False Belief demonstrated a ceiling effect and was not associated with any EF ability. Task Switching and 2-Back accounted for significant variance in Strange Stories. No EF task significantly predicted performance on TOMI-SR or interpersonal decentering. Both story comprehension tasks (False Belief and Strange Stories) were significantly associated, but these tasks were not correlated with either self-reported ToM or interpersonal decentering. Several unanticipated demographic associations were found; having more siblings and English proficiency accounted for significant variability in Strange Stories; education, presence or absence of self-disclosed autism diagnosis and mental health diagnosis explained a large portion of variance in TOMI-SR; interpersonal decentering maturity differed significantly between cisgender men and cisgender women. Lastly, interpersonal decentering number of interactions demonstrated an advantage for individuals without diagnosed or suspected autism diagnosis. This study raises critical concerns regarding measurement method error variance and variability of task demands in explaining cognitive mechanisms relevant to social cognitive processes.

[Truncated abstract] Background: Dementia, largely due to Alzheimer's disease (AD), is a major public health problem. The early identification of disease is an important challenge for clinicians because treatment of AD is now available. A simple and accurate means of stratifying risk for AD and identifying early disease is needed so that risk factor modification and treatment can occur optimally. To date, despite many attempts, an accurate means of standardising an approach to the assessment of subtle cognitive symptoms has not been developed. A subjective complaint of poor memory has been identified as a possible marker for underlying brain disease. This study examines the utility of neuropsychological scores, homocysteine levels, APOE genotyping and brain imaging as predictors of cognitive decline in individuals with subjective memory complaint (SMC). Method Eighty subjects with SMC were recruited from memory clinics and the community (MC: 1). Forty-two control subjects were also examined (MC: 0). CAMDEX was used to describe baseline clinical features. The CAMCOG was used as a global test of cognition and was administered annually for four years. At baseline, neuropsychological testing was administered. Cranial CT scanning, measurement of plasma homocysteine and APOE genotyping were completed. Categorical variables were analysed using chi-square according to Pearson's method. Continuous data was analysed using Student's t-tests and Mann-Whitney tests. A logistic regression model was used to identify independent contributors to the presence of memory complaint. Participants were then matched for age, gender and time to follow-up (up for three years) to determine longitudinal predictors of cognitive decline. ... Baseline CAMCOG scores were greater in the control group (MC:0 = 98.3 ? 2.8, MC:1 94.2 ? 5.5, Z ?4.46, p 0.000). There were no differences in neuropsychological scores, concentration of total plasma homocysteine, APOE genotype or brain scan measurements. Using the Wald stepwise selection method, logistic regression could not be established due to non-convergence regardless of whether or not the continuous variables were re-coded into dichotomous variables. A matching process that created 32 pairs of controls/subjects allowed follow-up analysis. The controls showed significant improvement with time on the CAMCOG unlike subjects (mean ? SD, controls 1.5 ?-3.0, Z - 2.61, p 0.01, subjects 0.2 ? 3.2, Z ? 0.24, p 0.81). The logistic regression analysis showed that group membership could not be defined by any single independent variable. When group membership was abandoned and those with stable scores were compared to those who declined no clear meaningful independent predictors of decline apart from age were identified. Conclusions: Methodological issues such as small sample size and inadequate follow up duration were identified that may have precluded identification of predictive factors for cognitive decline. The results indicate that complaints of memory problems are not associated with established risk factors for Alzheimer's disease and fail to predict objective cognitive decline over three years. Future studies should continue trying to identify robust predictors of cognitive decline in later life.