Categoría: Papers con abstracts

In this work, we explored convergent evidence supporting the fronto-striatal model of obsessive-compulsive disorder (FSMOCD) and the contribution of event-related potential (ERP) studies to this model. First, we considered minor modifications to the FSMOCD model based on neuroimaging and neuropsychological data. We noted the brain areas most affected in this disorder -anterior cingulate cortex (ACC), basal ganglia (BG) and orbito-frontal cortex (OFC)- and their related cognitive functions, such as monitoring and inhibition. Then, we assessed the ERPs that are directly related to the FSMOCD, including the error-related negativity (ERN), N200 and P600. Several OCD studies present enhanced ERN and N2 responses during conflict tasks as well as an enhanced P600 during working memory tasks. Evidence from ERP studies (especially regarding ERN and N200 amplitude enhancement), neuroimaging and neuropsychological findings suggests abnormal activity in the OFC, ACC and BG in OCD patients. Moreover, additional findings from these analyses suggest dorsolateral prefrontal and parietal cortex involvement, which might be related to executive function deficits. Thus, these convergent results suggest the existence of a self-monitoring imbalance involving inhibitory deficits and executive dysfunctions. OCD patients present an impaired ability to monitor, control, and inhibit intrusive thoughts, urges, feelings and behaviors. In the current model, this imbalance is triggered by an excitatory role of the BG (associated with cognitive or motor actions without volitional control) and inhibitory activity of the OFC as well as excessive monitoring of the ACC to block excitatory impulses. This imbalance would interact with the reduced activation of the parietal-DLPC network, leading to executive dysfunction. ERP research may provide further insight regarding the temporal dynamics of action monitoring and executive functioning in OCD.

INTRODUCCIÓN: La simulación de enfermedad mental ha sido un recurso utilizado por losimputados en causas penales con el fin de obtener beneficios ligados a la exención de la pena porun delito cometido, elección del lugar de alojamiento, trato o tratamiento recibido durante lareclusión. OBJETIVO: El presente trabajo intenta desarrollar un instrumento objetivo deevaluación que permita discriminar a los simuladores de enfermedad mental de los pacientespsiquiátricos dentro del ámbito penal. PACIENTES Y MÉTODO: Se evaluaron 92 derivaciones ala Unidad Psiquiátrica de Varones U.20 del Servicio Penitenciario Federal. Las evaluaciones serealizaron en la Sala de Observación y Evaluación Psiquiátrica (SOEP) por psiquiatras,neuropsicológos y trabajadores sociales. Se utilizaron criterios estandarizados de detección deSimulación, pruebas de diagnóstico clínico (MINI) y el Protocolo de Evaluación de Simulación(PES). RESULTADOS: El PES presentó, utilizando como punto de corte 17,5 puntos, un gradode sensibilidad de 92% y de especificidad de 95%. Los resultados obtenidos no han sidoinfluenciados por el nivel educativo, diagnóstico o causa penal del evaluado, tampoco por la edad o los antecedentes tóxicos del mismo. El protocolo no ha discriminado el resultado desimuladores vs. retrasos mentales moderados/grave. CONCLUSIONES: El PES resulta unaherramienta útil para el diagnóstico clínico de simulación dentro del ámbito penal. La correctadiferenciación de patologías psiquiátricas u otros problemas que requieran de atención(problemas institucionales, familiares, legales) resulta en un beneficio para el pacientepsiquiátrico prisionizado y el cuidado del espacio de tratamiento para los mismos.

We assessed cognitive performance and physical disability in 111 multiple sclerosis (MS) patients and 222 healthy controls in a multicenter study in Argentina to obtain the prevalence of cognitive impairment (CI) in a population of MS outpatients in Argentina. MS patients presented significantly lower scores in all Brief Repeatable Battery of Neuropsychology (BRB-N) tests than did the control group. The prevalence of CI was 43.2%. This study allowed us to obtain actual figures on the number of MS patients with CI in a Latin American sample. This validation is a very useful tool for clinical practice and for research studies to assess cognition in MS.

Introduction: The development of screening tools for the assessment of cognitive status in patients with dementia must be brief yet both highly sensitive and specific in order to ensure its clinical utility. In this sense, it is important to adapt tools widely used around the world to particular populations, allowing for a more proper validity of its use in everyday clinical practice. One of the most popular general cognitive screening tools is the Addenbrooke´s Cognitive Examination (ACE), which has been adapted and validated in multiple languages and populations. Objective: To assess the usefulness of the Peruvian version of the ACE in patients with dementia. Materials and methods: Healthy controls, patients with Alzheimer disease (AD) and patients with Frontotemporal Dementia (FTD) were assessed with the Peruvian version of the ACE, the ADAScog to determine dementia severity, and a complete neuropsychological battery. Results: The Peruvian version of the ACE showed very good internal con- sistency, strong concurrent validity as revealed by significant correlations between the ACE total score and both the MMSE and ADAScog. The ACE was able to differentiate healthy controls from patients with dementia with high discriminatory accuracy. Using a cut-off score of 86 (out of 100), the ACE was exhibited a sensitivity of 100% and a specificity of 100%.

We compared the utility of two executive-function brief screening tools, the Institute of Cognitive Neurology (INECO) Frontal Screening (IFS) and the Frontal Assessment Battery (FAB), in their ability to detect executive dysfunction in a group of behavioral variant frontotemporal dementia (bv-FTD, n = 25) and Alzheimer’s disease (AD, n = 25) patients in the early stages of their disease and in comparison to a group of age, gender, and education-matched controls (n = 26). Relative to the FAB, the IFS showed (a) better capability to differentiate between types of dementia; (b) higher sensitivity and specificity for the detection of executive dysfunction; (c) stronger correlations with standard executive tasks. We conclude that while both tools are brief and specific for the detection of early executive dysfunction in dementia, the IFS is more sensitive and specific in differentiating bvFTD from AD, and its use in everyday clinical practice can contribute to the differential diagnosis between types of dementia.

INTRODUCTION: The processing of the emotion of disgust is attributed to the insular cortex (IC), which is also responsible for social emotions and higher-cognitive functions. We distinguish the role of the IC from its connections in regard to these functions through the assessment of emotions and social cognition in a double case report. These subjects were very rare cases that included a focal IC lesion and a subcortical focal stroke affecting the connections of the IC with frontotemporal areas. MATERIALS & METHODS: Both patients and a sample of 10 matched controls underwent neuropsychological and affective screening questionnaires, a battery of multimodal basic emotion recognition tests, an emotional inference disambiguation task using social contextual clues, an empathy task and a theory of mind task. RESULTS: The insular lesion (IL) patient showed no impairments in emotion recognition and social emotions and presented with a pattern of delayed reaction times (RTs) in a subset of both groups of tasks. The subcortical lesion (SL) patient was impaired in multimodal aversive emotion recognition, including disgust, and exhibited delayed RTs and a heterogeneous pattern of impairments in subtasks of empathy and in the contextual inference of emotions. CONCLUSIONS: Our results suggest that IC related networks, and not the IC itself, are related to negative emotional processing and social emotions. We discuss these results with respect to theoretical approaches of insular involvement in emotional and social processing and propose that IC connectivity with frontotemporal and subcortical regions might be relevant for contextual emotional processing and social cognition.

Over the past five to ten years, neuroimaging capability for neurodegenerative diseases has made remarkable progress. However, debate remains as to the true clinical utility of these advanced and costly investigations. Not only is the place of these tests in diagnostic algorithms unclear, but the access to them varies both within and between countries. We sought to gather informed opinion from recognized leaders in the field who can combine both an academic and a clinical perspective on the use of neuroimaging in their own countries. Opinion is presented from Scotland, Argentina, the Czech Republic, France, the USA and Australia. The emerging consensus was one of ongoing caution. While in most countries there was a sense that the use of more advanced imaging techniques was growing, their hour has not yet cometh. However, these techniques, rather than falling from the Ivory Tower, should descend slowly step by step onto fertile and receptive clinics from where better clinical guidelines will emerge.

Postural deformities are frequent and disabling complications of Parkinson’s disease (PD) and atypical parkinsonism. These deformities include camptocormia, antecollis, Pisa syndrome, and scoliosis. Recognition of specific postural syndromes might have differential diagnostic value in patients presenting with parkinsonism. The evidence to date suggests that postural deformities have a multifactorial pathophysiology. Contributing factors include muscular rigidity; axial dystonia; weakness caused by myopathy; body scheme defects due to centrally impaired proprioception; and structural changes in the spine. The relative contribution of these different factors varies between patients and across specific syndromes. Improved understanding of the mechanisms underlying postural deformities in PD might ultimately lead us to more effective management strategies for these disabling and drug-refractory complications.

Previous research on semantic dementia (SD) has demonstrated a link between conceptual representations and ability on a range of ´non-semantic´ tasks, both verbal and nonverbal. In all cases, SD patients perform well on items that conform to the underlying statistical ´surface´ structure of the domain in question but poor performance on items that are atypical with respect to these statistics. For such items, there is a strong tendency for the patients´ erroneous responses to reflect the more typical pattern. To date, most research on this topic has been conducted with English-speaking patients, and where extended to non-English languages, directly comparable aspects of each language have been probed. In this study we tested the generalisation of this theory by probing performance on an aspect of Spanish with no analogue in English (grammatical gender). As predicted, Spanish SD patients provided the correct gender to high frequency words or where the phonology of the noun strongly predicted the gender. For low frequency, atypical nouns, however, the patients made many more errors (preferring the statistically typical gender). As expected, performance on nouns with atypical grammatical gender was strongly correlated with the degree of semantic impairment across the case-series of SD patients.

The results not only provide another example of the critical relationship between semantic memory and ´non-semantic´ cognition, but also indicate that this theoretical framework generalises to novel aspects of non-English languages – suggesting that the phenomenon is based on brain-general mechanisms.

Several case reports have linked solvent exposure to Parkinson disease (PD), but few studies have assessed associations with specific agents using an analytic epidemiologic design. We tested the hypothesis that exposure to specific solvents is associated with PD risk using a discordant twin pair design. METHODS: Ninety-nine twin pairs discordant for PD ascertained from the National Academy of Sciences/National Research Council World War II Veteran Twins Cohort were interviewed regarding lifetime occupations and hobbies using detailed job task-specific questionnaires. Exposures to 6 specific solvents selected a priori were estimated by expert raters unaware of case status. RESULTS: Ever exposure to trichloroethylene (TCE) was associated with significantly increased risk of PD (odds ratio [OR], 6.1; 95% confidence interval [CI] 1.2-33; p = 0.034), and exposure to perchloroethylene (PERC) and carbon tetrachloride (CCl(4) ) tended toward significance (respectively: OR, 10.5; 95% CI, 0.97-113; p = 0.053; OR, 2.3; 95% CI, 0.9-6.1; p = 0.088). Results were similar for estimates of exposure duration and cumulative lifetime exposure. INTERPRETATION: Exposure to specific solvents may increase risk of PD. TCE is the most common organic contaminant in groundwater, and PERC and CCl(4) are also ubiquitous in the environment. Our findings require replication in other populations with well-characterized exposures, but the potential public health implications are substantial.