Categoría: Papers con abstracts

Pavlovian trace conditioning depends on the temporal gap between the conditioned and unconditioned stimuli. It requires, in mammals, functional medial temporal lobe structures and, in humans, explicit knowledge of the temporal contingency. It is therefore considered to be a plausible objective test to assess awareness without relying on explicit reports. We found that individuals with disorders of consciousness (DOCs), despite being unable to report awareness explicitly, were able to learn this procedure. Learning was specific and showed an anticipatory electromyographic response to the aversive conditioning stimulus, which was substantially stronger than to the control stimulus and was augmented as the aversive stimulus approached. The amount of learning correlated with the degree of cortical atrophy and was a good indicator of recovery. None of these effects were observed in control subjects under the effect of anesthesia (propofol). Our results suggest that individuals with DOCs might have partially preserved conscious processing, which cannot be mediated by explicit reports and is not detected by behavioral assessment.

In order to evaluate the relationship between systemic inflammatory response and mortality in the older hospitalized patient, we developed a prospective cohort study in which we evaluated a nutritional score (SGA), years of instruction, functional status, organic failure (Marshall), presence of sepsis, comorbidities (Charlson), cognitive state (MMSE), albumin, erythrocyte sedimentation rate and mortality. Fifty two patients were included, 19 men (36.5%) and 33 women (63.5%), mean age was 80 (Interquartile Range 12.5) years. 29 (55.8%) patients were well-nourished and 23 (44.2%) malnourished, 53.8% of patients developed sepsis at admission or during hospitalization. Total nosocomial mortality was 7.7 % (n = 4) and one-year mortality was 31.8% (n = 14). Comparative analyses showed older age (80 vs. 78; p = 0.012), less years of instruction (7 vs. 8; p = 0.027), lower MMST (14 vs. 27; p = 0.017), lower previous functional status (21 vs. 32; p < 0.0001), lower albumin (3 vs. 3.35; p = 0.014) and higher organic failure score at admission (3 vs. 1; p = 0.01) with more number of affected organs (2 vs. 1; p = 0.003) in malnourished patients compared to well nourished ones. Higher incidence of sepsis -at admission or during hospitalization- (73.9% vs. 37.9%; p = 0.01) and more severe stages of sepsis were also observed in malnourished patients. One-year mortality was significantly higher in malnourished (52.2% vs. 9.5%, log rank test = 0.002). In conclusion, malnourished patients presented greater systemic inflammatory response.

The aim of this investigation was to evaluate improvement of executive functions after shunt surgery in patients with early normal pressure hydrocephalus (NPH). Patients with NPH were assessed before and after shunt surgery with tests shown to be sensitive to damage to the prefrontal cortex (PFC). Significant differences were found between basal and follow-up performances on the Boston Naming Test, the backwards digits span, Part B of the Trail Making Test, and the number of words produced on the phonological fluency task. In conclusion, our study reveals that patients with NPH who respond positively to continuous slow lumbar cerebral spinal fluid drainage and receive a ventriculoperitoneal shunt implant, improve their performance on tasks of executive function. Due to the high demand for this form of mental processing in real-life complex scenarios, and based on the severe executive deficits present in both demented and non-demented NPH patients, we encourage the assessment of executive functions in this clinical group.

It is currently accepted that there is a subset of patients diagnosed with Alzheimer’s disease (AD) who show executive functioning (EF) impairments even in the earlier stages. These patients have been shown to present distinct psychiatric, behavioral, occupational, and even histopathological profiles. We assessed thirty patients with AD on two tasks of verbal memory (Logical Memory – LM, and the Rey Auditory-Verbal Learning Task – RAVLT), as well as classical tests of EF. AD patients were classified into either a spared EF (SEF) group if they showed impaired performance (z < -1.5 SD) in none or only one of the executive tests, or into an impaired EF (IEF) group if they showed impaired performance on two or more tasks of EF. Their performance was compared with fourteen healthy controls. SEF showed significantly more years of education than IEF, but the groups did not differ significantly on age, gender, mood symptoms, or performance on general screening tests or attentional tasks. With education as a covariate, both AD groups differed from controls on all measures of memory, but a significant difference was found between SEF and IEF patients only on the recognition phases of both logical memory (p < 0.01) and RAVLT (p = 0.02). Recognition scores significantly correlated with performance on executive tasks. Early AD patients who preserve their EF seem to have an advantage in their ability to recognize information that has been previously presented over patients with impaired EF. Such advantage seems to be strongly associated with executive performance.

Traditional cognitive tests may not be sensitive for the early detection of executive and social cognitive impairments in the behavioural variant of frontotemporal dementia. The aim of this study was to detect specific executive and social cognitive deficits in patients with early behavioural variant frontotemporal dementia using a battery of tests previously shown to be sensitive to frontal lobe dysfunction. Behavioural variant frontotemporal dementia patients and paired controls were assessed with a complete standard neuropsychological battery evaluating attention, memory, visuospatial abilities, language and executive functions. All participants were then assessed with our Executive and Social Cognition Battery, which included Theory of Mind tests (Mind in the Eyes, Faux Pas), the Hotel Task, Multiple Errands Task-hospital version and the Iowa Gambling Task for complex decision-making. Patients were divided into two groups according to their Addenbrooke’s Cognitive Examination scores, a measure of general cognitive status. Low Addenbrooke’s Cognitive Examination patients differed from controls on most tasks of the standard battery and the Executive and Social Cognition Battery. While high Addenbrooke’s Cognitive Examination patients did not differ from controls on most traditional neuropsychological tests, significant differences were found between this high-functioning behavioural variant of frontotemporal dementia group and controls on most measures of our Executive and Social Cognition Battery. Our results suggest that the Executive and Social Cognition Battery used in this study is more sensitive in detecting executive and social cognitive impairment deficits in early behavioural variant of frontotemporal dementia than the classical cognitive measures.

Many tests of specific ‘executive functions’ show deficits after frontal lobe lesions. These deficits appear on a background of reduced fluid intelligence, best measured with tests of novel problem solving. For a range of specific executive tests, we ask how far frontal deficits can be explained by a general fluid intelligence loss. For some widely used tests, e.g. Wisconsin Card Sorting, we find that fluid intelligence entirely explains frontal deficits. When patients and controls are matched on fluid intelligence, no further frontal deficit remains. For these tasks too, deficits are unrelated to lesion location within the frontal lobe. A second group of tasks, including tests of both cognitive (e.g. Hotel, Proverbs) and social (Faux Pas) function, shows a different pattern. Deficits are not fully explained by fluid intelligence and the data suggest association with lesions in the right anterior frontal cortex. Understanding of frontal lobe deficits may be clarified by separating reduced fluid intelligence, important in most or all tasks, from other more specific impairments and their associated regions of damage.

Real life Executive Deficits in Patients with Focal Vascular Lesions Affecting the Cerebellum. Autores Manes F, Ruiz Villamil A, Ameriso S, Roca M, Torralva T.  Año 2009 Journal  Manes F, Ruiz Villamil A, Ameriso S, Roca M, Torralva T.  Volumen 283(1-2): 95-98 Abstract   Otra información    

A large proportion of human social neuroscience research has focused on the issue of decision-making. Impaired decision-making is a symptomatic feature of a number of neurodegenerative diseases, but the nature of these decision-making deficits depends on the particular disease. Thus, examining the qualitative differences in decision-making impairments associated with different neurodegenerative diseases could provide valuable information regarding the underlying neural basis of decision-making. Nevertheless, few comparative reports of decision-making across patient groups exist. In this Review, we examine the neuroanatomical substrates of decision-making in relation to the neuropathological changes that occur in Alzheimer disease, frontotemporal dementia, Parkinson disease and Huntington disease. We then examine the main findings from studies of decision-making in these neurodegenerative diseases. Finally, we suggest a number of recommendations that future studies could adopt to aid our understanding of decision-making cognition.

BACKGROUND: A 69 year-old woman presented to an interdisciplinary medical group with pathological gambling, and went on to develop disinhibition, loss of empathy, and perseverative, stereotyped and ritualistic behavior. An initial neuropsychological evaluation showed selective impairment on the Iowa Gambling Task similar to that of patients with behavioral variant frontotemporal dementia, despite normal performance on standard neuropsychological tasks. MRI scans showed frontal lobe atrophy, which was consistent with findings on hexamethylpropyleneamine oxime single photon emission CT (HMPAO-SPECT). INVESTIGATIONS: Physical examination, neuropsychiatric and neuropsychological assessments, MRI brain scan, HMPAO-SPECT. DIAGNOSIS: Behavioral variant frontotemporal dementia. MANAGEMENT: Pharmacological treatment with the selective serotonin reuptake inhibitor paroxetine for impulsive behavior and carbamazepine to stabilize mood. The patient and her family also received counseling to advise on behavioral and legal issues.

BACKGROUND: A reliable and valid questionnaire for screening restless legs syndrome (RLS) is essential for determining accurate estimates of disease frequency. In a 2002 NIH-sponsored workshop, experts suggested three mandatory questions for identifying RLS in epidemiologic studies. We evaluated the reliability and validity of this RLS-NIH questionnaire in a community-based sample and concurrently developed and evaluated the utility of an expanded screening questionnaire, the RLS-EXP. METHODS: The study was conducted at Kaiser Permanente of Northern California and the Stanford University Sleep Clinic. We evaluated test-retest reliability in a random sample of subjects with prior physician-assigned RLS (n=87), subjects with conditions frequently misclassified as RLS (n=31), and healthy subjects (n=9). Validity of both instruments was evaluated in a random sample of 32 subjects, and in-person examination by two RLS specialists was used as the gold standard. RESULTS: For the first three RLS-NIH questions, the kappa statistic for test-retest reliability ranged from 0.5 to 1.0, and sensitivity and specificity was 86% and 45%, respectively. For the subset of five questions on RLS-EXP that encompassed cardinal features for diagnosing RLS, kappas were 0.4-0.8, and sensitivity and specificity were 81% and 73%, respectively. CONCLUSIONS: Sensitivity of RLS-NIH is good; however, the specificity of the instrument is poor when examined in a sample that over-represents subjects with conditions that are commonly misclassified as RLS. Specificity can be improved by including separate questions on cardinal features, as used in the RLS-EXP, and by including a few questions that identify RLS mimics, thereby reducing false positives.