Relación entre atrofia cortical difusa y desempeño cognitivo : estudio en población mayor de 60 años en un hospital universitario en la ciudad de Bogotá

El presente trabajo tuvo como objetivo evaluar la existencia de la relación entre la atrofia cortical difusa objetivada por neuroimagenes cerebrales y desempeños cognitivos determinados mediante la aplicación de pruebas neuropsicológicas que evalúan memoria de trabajo, razonamiento simbólico verbal y memoria anterógrada declarativa. Participaron 114 sujetos reclutados en el Hospital Universitario Mayor Méderi de la ciudad de Bogotá mediante muestreo de conveniencia. Los resultados arrojaron diferencias significativas entre los dos grupos (pacientes con diagnóstico de atrofia cortical difusa y pacientes con neuroimagenes interpretadas como dentro de los límites normales) en todas las pruebas neuropsicológicas aplicadas. Respecto a las variables demográficas se pudo observar que el grado de escolaridad contribuye como factor neuroprotector de un posible deterioro cognitivo. Tales hallazgos son importantes para determinar protocoles tempranos de detección de posible instalación de enfermedades neurodegenerativas primarias.

Structure and function of declarative and nondeclarative memory systems

This article reviews recent studies of memory systems in humans and nonhuman primates. Three major conclusions from recent work are that (i) the capacity for nondeclarative (nonconscious) learning can now be studied in a broad array of tasks that assess classification learning, perceptuomotor skill learning, artificial grammar learning, and prototype abstraction; (ii) cortical areas adjacent to the hippocampal formation, including entorhinal, perirhinal, and parahippocampal cortices, are an essential part of the medial temporal lobe memory system that supports declarative (conscious) memory; and (iii) in humans, bilateral damage limited to the hippocampal formation is nevertheless sufficient to produce severe anterograde amnesia and temporally graded retrograde amnesia covering as much as 25 years.

Cerebellar lesions: is there a lateralisation effect on memory deficits?

BACKGROUND: Until recently, neurosurgeons eagerly removed cerebellar lesions without consideration of future cognitive impairment that might be caused by the resection. In children, transient cerebellar mutism after resection has lead to a diminished use of midline approaches and vermis transection, as well as reduced retraction of the cerebellar hemispheres. The role of the cerebellum in higher cognitive functions beyond coordination and motor control has recently attracted significant interest in the scientific community, and might change the neurosurgical approach to these lesions. The aim of this study was to investigate the specific effects of cerebellar lesions on memory, and to assess a possible lateralisation effect. METHODS: We studied 16 patients diagnosed with a cerebellar lesion, from January 1997 to April 2005, in the "Centre Hospitalier Universitaire Vaudois (CHUV)", Lausanne, Switzerland. Different neuropsychological tests assessing short term and anterograde memory, verbal and visuo-spatial modalities were performed pre-operatively. RESULTS: Severe memory deficits in at least one modality were identified in a majority (81%) of patients with cerebellar lesions. Only 1 patient (6%) had no memory deficit. In our series lateralisation of the lesion did not lead to a significant difference in verbal or visuo-spatial memory deficits. FINDINGS: These findings are consistent with findings in the literature concerning memory deficits in isolated cerebellar lesions. These can be explained by anatomical pathways. However, the cross-lateralisation theory cannot be demonstrated in our series. The high percentage of patients with a cerebellar lesion who demonstrate memory deficits should lead us to assess memory in all patients with cerebellar lesions.

Suicide behavior and neuropsychological assessment of type I bipolar patients

Background: Neuropsychological deficits are often described in patients with bipolar disorder (BID). Some symptoms and/or associated characteristics of BD can be more closely associated to those cognitive impairments. We aimed to explore cognitive neuropsychological characteristics of type I bipolar patients (BPI) in terms Of lifetime Suicide attempt history. Method: We studied 39 BPI Outpatients compared with 53 healthy controls (HC) matched by age, educational and intellectual level. All Subjects were submitted to a neuropsychological assessment of executive functions, decision-making and declarative episodic memory. Results: When comparing BD1 patients, regardless of suicide attempt history or HC, we observed that bipolar patients performed worse than controls oil measures of memory, attention, executive functions and decision-making, Patients with a history of suicide attempt performed worse than non-attempters on measures of decision-making and there were a significant negative correlation between the number of suicide attempts and decision-making results (block 3 and net score). We also found significant Positive correlation between the number Of Suicide attempts and amount Of errors in Stroop Color Word Test (part 3). Limitations: The sample Studied call be considered small and a potentially confounding variable - medication status - were not controlled. Conclusion: Our results show the presence of neuropsychological deficits in memory, executive functions, attention and decision-making in BPI patients. Suicide attempts BPI scored worse than non-suicide attempt Bill oil measures of decision-making. More suicide attempts were associated with a worse decision-making process. Future research should explore the relationship between the association between this specific cognitive deficits in BPIs, serotonergic function and suicide behavior in bipolar patients as well other diagnostic groups. (C) 2009 Elsevier B.V. All rights reserved.

Le blocage de la consolidation et de la reconsolidation des souvenirs émotionnels chez l'humain à l'aide du propranolol

Une récente théorie de la mémoire a proposé que lorsqu'un souvenir déjà bien consolidé est réactivé, il redevient labile et susceptible aux modifications avant d'être restabilisé (reconsolidé) en mémoire à long terme. Ce nouveau modèle réfute le modèle classique de la consolidation qui propose qu'une fois consolidés, les souvenirs soient permanents et donc résistants aux effets des agents amnésiques. Les études validant la théorie de la reconsolidation abondent chez les animaux, mais encore peu d'études ont été réalisées chez les humains. L'objectif de cette thèse est de vérifier, dans une population de sujets sains et de sujets souffrant de trouble de stress post-traumatique (TSPT), l'efficacité d'un agent pharmacologique, le propranolol (un β-bloquant noradrénergique) à atténuer des souvenirs émotionnels nouvellement acquis ou déjà bien consolidés. Plus spécifiquement, nous avons mené un essai clinique contrôlé à double insu chez des sujets sains en leur administrant du propranolol (vs du placebo) lors de l'acquisition d'un nouveau souvenir et une semaine plus tard, lors de sa réactivation. L'objectif du premier article était d'évaluer l'efficacité du propranolol à diminuer la consolidation et la reconsolidation d'un souvenir émotionnel. Par ailleurs, puisque les études chez les animaux ont démontré que ces deux processus mnésiques s'effectuent à l'intérieur d'une fenêtre temporelle précise, le moment de l'administration du propranolol fut pris en considération. Les résultats ont démontré que le propranolol est en mesure de diminuer la consolidation et la reconsolidation d'une histoire émotionnelle tel que démontré par un pourcentage de bonnes réponses plus faible que le groupe contrôle lors des rappels. Toutefois, pour que cet effet soit observé, le propranolol doit être administré une heure avant la présentation des stimuli, pour la consolidation et une heure avant leur réactivation, pour la reconsolidation. En outre, les études portant sur la consolidation et la reconsolidation chez les animaux et chez les humains obtiennent parfois des résultats contradictoires. Ceci pourrait s'expliquer par le type de stimuli utilisé. Ainsi, l'objectif du second article était de préciser quel type d'information est le plus susceptible d'être affecté par le propranolol lors de son acquisition (consolidation) et lors de sa réactivation (reconsolidation). Pour ce faire, les éléments de l'histoire émotionnelle ont été divisés en fonction de leur valence (émotionnel ou neutre) et de leur centralité (central ou périphérique). Les résultats ont démontré le propranolol affecte l'ensemble des informations centrales lors du blocage de la consolidation, mais qu'il affecte plus spécifiquement les éléments émotionnels centraux lors de la reconsolidation. Notre groupe ayant précédemment démontré que le traitement avec le propranolol est en mesure de réduire les symptômes de TSPT chez une population clinique, nous nous sommes interrogés sur son efficacité à diminuer la mémoire implicite d'un événement traumatique. Le propranolol a été administré aux participants à 6 reprises (une fois par semaine sur une période de 6 semaines) lors de la réactivation de leur trauma. Les résultats ont révélé que le traitement avec le propranolol est en mesure de diminuer la réponse psychophysiologique des participants à l'écoute du compte rendu de leur trauma une semaine et 4 mois suivant la fin du traitement. En somme, cette thèse démontre que le propranolol est en mesure de bloquer la consolidation et la reconsolidation de souvenirs émotionnels chez l'humain lorsqu'il est administré une heure avant l'acquisition ou la réactivation des souvenirs. Il arrive en outre à atténuer un souvenir déclaratif émotionnel chez des sujets sains, mais également un souvenir implicite chez des sujets souffrant de TSPT. Ainsi, ces résultats ouvrent la voie à la création de nouveaux traitements pour les psychopathologies ayant comme étiologie un souvenir émotionnel intense.

Exercise and cognitive functions in Parkinson's disease: Gender differences and disease severity

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cognitive functioning in the schizophrenia prodrome

In the last decade, there has been an increasing interest in cognitive alterations during the early course of schizophrenia. From a clinical perspective, a better understanding of cognitive functioning in putative at-risk states for schizophrenia is essential for developing optimal early intervention models. Two approaches have more recently been combined to assess the entire course of the initial schizophrenia prodrome: the predictive "basic symptom at-risk" (BS) and the ultra high-risk (UHR) criteria. Basic symptoms are considered to be present during the entire disease progression, including the initial prodrome, while the onset of symptoms captured by the UHR criteria expresses further disease progression toward frank psychosis. The present study investigated the cognitive functioning in 93 subjects who met either BS or UHR criteria and thus were assumed to be at different points on the putative trajectory to psychosis. We compared them with 43 patients with a first episode of psychosis and to 49 help-seeking patient controls. All groups performed significantly below normative values. Both at-risk groups performed at intermediate levels between the first-episode (FE) group and normative values. The UHR group demonstrated intermediate performance between the FE and BS groups. Overall, auditory working memory, verbal fluency/processing speed, and declarative verbal memory were impaired the most. Our results suggest that cognitive impairments may still be modest in the early stages of the initial schizophrenia prodrome and thus support current efforts to intervene in the early course of impending schizophrenia because early intervention may prevent or delay the onset of frank psychosis and thus prevent further cognitive damage.

Efeito agudo do exercício físico associado a praxias ideomotoras sobre as concentrações séricas de cortisol e memória declarativa em indivíduos com idade entre 51 e 74 anos

Introduction: Several modifications are identified as aging, causing more or less limitation imposed by over the years. Among these, one can highlight the different degrees of cognitive decline, particularly memory that can involve the daily activities and the subject functionality. Studies have shown an association between levels of serum cortisol and stress imposed by the exercise on this. However, there are few studies that references the performance on cognitive aspects of declarative memory and cortisol on the exercise in the water with automatic and práxicos movements and moderate. Objective: Check the effect based on the acute physical exercise and práxicos automatic movements on the performance of visual declarative memory and in serum cortisol in subjects aged between 51 and 74 years. Materials and Methods: It builds a survey characterized as cross with a first sample of 32 physically active subjects aged between 51 and 74 years, divided into two exercise groups (March of Automatic Group - MAG and the March of Praxis Group - MPG). We used a probabilistic and random sampling for sample selection. Used the MMSE (Mini Mental State Examination) to check the general cognitive status, visual acuity test - optotypes chart "E" Rasquin and was even used the declarative visual memory test proposed by Nitrini and collaborators (1994), applying before motor stimulation and immediately after, and the day of blood collection with 2 ml for analysis of cortisol hormone. The normality and homogeneity were verified from the Shapiro-Wilk and Levene tests. Thus we adopted a descriptive statistics to characterize the sample. The Split-Plot ANOVA was used along with the paired t-test to verify the identified differences. We adopted a significance level of p <0.05. Results: It was observed that the groups (MAG and MPG) and the anthropometric variables, perceived exertion, education, cognitive assessment and visual acuity showed no significant differences (p > 0.05), showing that the groups are homogeneous, with variables and similar means. After the stimulation session, lasting 30 min, it was observed that the amount of hits for Δ of declarative memory questionnaire visual images increased, presenting significant for both groups (MAG, p < 0.001; MPG, p = 0.042). The same was observed for cortisol concentration with a reduction in the levels immediately after the stimulus (MAG and MPG, p < 0.001). Conclusion: The results showed that the exercises proposed in its acute effect provide significantly memories of gains and also showed a reduction in cortisol levels.

Populating ACT-R's Declarative Memory with Internet Statistics

Decision situations are often characterized by uncertainty: we do not know the values of the different options on all attributes and have to rely on information stored in our memory to decide. Several strategies have been proposed to describe how people make inferences based on knowledge used as cues. The present research shows how declarative memory of ACT-R models could be populated based on internet statistics. This will allow to simulate the performance of decision strategies operating on declarative knowledge based on occurrences and co-occurrences of objects and cues in the environment.

Enhancement of declarative memory associated with emotional content in a Brazilian sample

Several studies have documented that emotional arousal may enhance long-term memory. This is an adaptation of a paradigm previously used in North American and European samples in investigations of the influence of emotion on long-term retention. A sample of 46 healthy adults of high and low educational levels watched a slide presentation of stories. A randomly assigned group watched a story with an arousing content and another group watched a neutral story. The stories were matched for structure and comprehensibility and the set and order of the 11 slides were the same in both conditions. Immediately after viewing the slide presentation, the participants were asked to rate the emotionality of the narrative. The arousing narrative was rated as being more emotional than the neutral narrative (t (44) = -3.6, P<0.001). Ten days later subjects were asked to remember the story and answer a multiple-choice questionnaire about it. The subjects who watched the arousing story had higher scores in the free recall measure (t (44) = -2.59, P<0.01). There were no differences between groups in the multiple-choice test of recognition memory (t (44) = 0.26). These findings confirm that an emotional arousing content enhances long-term declarative memory and indicate the possibility of applying this instrument to clinical samples of various cultural backgrounds.

The deferred imitation task as a nonverbal measure of declarative memory.

We tested amnesic patients, patients with frontal lobe lesions, and control subjects with the deferred imitation task, a nonverbal test used to demonstrate memory abilities in human infants. On day 1, subjects were given sets of objects to obtain a baseline measure of their spontaneous performance of target actions. Then different event sequences were modeled with the object sets. On day 2, the objects were given to the subjects again, first without any instructions to imitate the sequences, and then with explicit instructions to imitate the actions exactly as they had been modeled. Control subjects and frontal lobe patients reproduced the events under both uninstructed and instructed conditions. In contrast, performance by the amnesic patients did not significantly differ from that of a second control group who had the same opportunities to handle the objects but were not shown the modeled actions. These findings suggest that deferred imitation is dependent on the brain structures essential for declarative memory that are damaged in amnesia, and they support the view that infants who imitate actions after long delays have an early capacity for long-term declarative memory.

Relationship Between Cortisol Levels and Memory Performance may be Modulated by the Presence or Absence of Cognitive Impairment: Evidence from Healthy Elderly, Mild Cognitive Impairment and Alzheimer`s Disease Subjects

An inverted U-shape function between cortisol levels and memory performance has been reported in studies on both young animals and humans. Yet little is known about this relationship in normal aging or in older subjects with cognitive impairment. This issue is particularly significant since increased levels of cortisol have been reported in Alzheimer`s disease (AD). The present study examined the association between cortisol levels and visual memory performance in healthy subjects as well as in individuals presenting mild cognitive impairment (MCI) or AD. Salivary cortisol was measured in 40 healthy elderly subjects, 31 individuals with amnestic MCI, and 40 subjects with mild probable AD. Memory performance was evaluated using the Brief Cognitive Screening Battery. Higher cortisol levels were associated with better memory performance in healthy elderly (p = 0.005), while higher cortisol levels were correlated with poorer memory performance in MCI subjects (p = 0.011). No correlation between cortisol and memory was found in the AD group (p > 0.05). These results suggest that the relationship between cortisol levels and memory performance in the aging process could vary according to the presence or absence of cognitive impairment.

Memory with emotional content, brain amygdala and Alzheimer`s disease

Objectives - A highly adaptive aspect of human memory is the enhancement of explicit, consciously accessible memory by emotional stimuli. We studied the performance of Alzheimer`s disease (AD) patients and elderly controls using a memory battery with emotional content, and we correlated these results with the amygdala and hippocampus volume. Methods - Twenty controls and 20 early AD patients were subjected to the International Affective Picture System (IAPS) and to magnetic resonance imaging-based volumetric measurements of the medial temporal lobe structures. Results - The results show that excluding control group subjects with 5 or more years of schooling, both groups showed improvement with pleasant or unpleasant figures for the IAPS in an immediate free recall test. Likewise, in a delayed free recall test, both the controls and the AD group showed improvement for pleasant pictures, when education factor was not controlled. The AD group showed improvement in the immediate and delayed free recall test proportional to the medial temporal lobe structures, with no significant clinical correlation between affective valence and amygdala volume. Conclusion - AD patients can correctly identify emotions, at least at this early stage, but this does not improve their memory performance.

Working memory correlates of three symptom clusters in schizophrenia

This study was designed to examine whether discrete working memory deficits underlie positive, negative and disorganised symptoms of schizophrenia. Symptom dimension ratings were assigned to 52 outpatients with schizophrenia (ICD-10 criteria), using items drawn from the Positive and Negative Syndrome Scale (PANSS). Linear regression and correlational analyses were conducted to examine whether symptom dimension scores were related to performance on several tests of working memory function. Severity of negative symptoms correlated with reduced production of words during a verbal fluency task, impaired ability to hold letter and number sequences on-line and manipulate them Simultaneously, reduced performance during a dual task, and compromised visuospatial working memory under distraction-free conditions. Severity of disorganisation symptoms correlated with impaired visuospatial working memory under conditions of distraction, failure of inhibition during a verbal fluency task, perseverative responding on a test of set-shifting ability, and impaired ability to judge the veracity of simple declarative statements. Severity of positive symptoms was uncorrelated with performance on any of the measures examined. The present study provides evidence that the positive, negative and disorganised symptom dimensions of the PANSS constitute independent clusters, associated with unique patterns of working memory impairment. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Declarative approach to data extraction of web pages

Thesis submitted to Faculdade de Ciências e Tecnologia of the Universidade Nova de Lisboa, in partial fulfilment of the requirements for the degree of Master in Computer Science