Activation of the arousal response can impair performance on a simple motor task. (25/634)

The purpose of this study was to determine the effect of arousal in men and women on the moment-to-moment performance of a simple motor task. We examined the control of a precision task in the presence and absence of imposed stressors. Twenty-nine subjects (14 men, 15 women; 18--44 yr) were randomly assigned to either a control group or one of two stressor groups, Mental Math or Electric Shock. Subjects presented with Math and Shock stressors, which lasted 10 min, experienced significant increases in cognitive and physiological arousal compared with baseline and control subjects. Heart rate, systolic blood pressure, and electrodermal activity were elevated 5--80% with presentation of the stressors, whereas diastolic blood pressure and salivary cortisol were unchanged. The greater levels of cognitive and physiological arousal were associated with reductions in steadiness of a pinch grip for the Shock subjects (approximately 130% reduction from baseline) but not for the subjects in the Math group, who experienced heightened arousal but no change in steadiness (10% reduction from baseline). Although women exhibited more of a reduction in steadiness than men, the effect was largely unrelated to the magnitude of the change in arousal.  (+info)

The nature of semantic memory deficits in Alzheimer's disease: new insights from hyperpriming effects. (26/634)

While semantic memory deficits are a common landmark of Alzheimer's disease, the nature of these impairments remains to be clarified. Implicit tasks which assess semantic priming effects are often used to understand semantic deficits in Alzheimer's disease, but they have led to unclear conclusions because of methodological problems such as intervention of attentional mechanisms. To explore the effects of semantic priming in Alzheimer's disease and their relationship with semantic memory deficits, we used two tasks, one implicit and the other explicit. The implicit task was a lexical decision task to assess semantic priming, and in which pairs of words had coordinate (tiger-lion) or attribute relationships (zebra-stripe). The explicit task was a semantic knowledge task composed of namings and questions involving superordinate categories and attribute knowledge of concepts. The two tasks systematically assessed the integrity of the same concepts. This protocol was given to 53 Alzheimer's disease patients with mild to moderate dementia and to 20 controls. The Alzheimer's disease group as a whole obtained significantly greater priming effects (hyperpriming) than controls in the coordinate condition, and equivalent priming in the attribute condition. In the coordinate condition, a subgroup of 26 patients, with attribute knowledge deficits, had larger priming effects than both a subgroup without semantic deficits and the control group. These results show that in Alzheimer's disease the semantic priming effects vary according to the degree of attribute loss, and the presence of hyperpriming would reflect semantic memory deficits. This study unravels the fine-grained structure of semantic memory disturbances in Alzheimer's disease with mild to moderate dementia, affecting initially the attributes of concepts within a hierarchical network in which superordinate concepts remain preserved.  (+info)

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: decrease in regional cerebral blood volume in hyperintense subcortical lesions inversely correlates with disability and cognitive performance. (27/634)

BACKGROUND AND PURPOSE: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an arteriopathic syndrome related to a genetic defect on chromosome 19. Characteristic changes in CADASIL can be observed onT2-weighted MR images in the subcortical white matter. The purpose of this study was to measure changes of regional cerebral blood volume (rCBV) with dynamic contrast-enhanced MR imaging and to correlate the changes to disability and cognitive performance. METHODS: We obtained rCBV measurements of 24 individuals with proven CADASIL on a 1.5-T MR imaging unit. A susceptibility-weighted MR imaging sequence was used for bolus tracking. Principles of the indicator dilution theory were applied to estimate values of absolute rCBV (mL/100 g). Disability was determined by using the Rankin scale, and overall cognitive performance was assessed by using the Mini-Mental State Examination. RESULTS: The mean rCBV in the subcortical white matter that was hyperintense on the T2-weighted images (2.7 +/- 0.8 mL/100 g) was significantly lower than the rCBV in the white matter that appeared normal on the T2-weighted images (4.4 +/- 1.3 mL/100 g) (P <.05). The mean rCBV in the gray matter was within the normal range (8.3 +/- 1.7 mL/100 g). Both cognitive impairment and disability negatively correlated with rCBV in the subcortical white matter that was hyperintense (P <.05) but not with rCBV in the normal appearing white matter. rCBV did not correlate with age. CONCLUSION: rCBV measured in the hyperintense subcortical white matter in individuals with CADASIL was decreased and inversely correlated with disability and cognitive impairment.  (+info)

Preclinical syndromes predict dementia: the Sydney older persons study. (28/634)

OBJECTIVES: To identify if preclinical syndromes for Alzheimer's disease, vascular dementia, and Parkinson's disease and related dementias exist. Identification of dementia at early or even preclinical stages has important implications for treatment. METHODS: A community dwelling sample of 647 subjects aged 75 and over at recruitment were followed up for a mean period of 3.19 years (range 2.61 to 4.51 years). Each subject was asked to participate in a medical assessment which included a standardised medical history examining both past and current health and medication usage; a neuropsychological battery (mini mental state examination, Reid memory test, verbal fluency, subsets of the Boston naming test and similarities, clock drawing and copied drawings) and physical examination. Preclinical syndromes for the three predominant dementias (Alzheimer's disease, vascular dementia and Parkinson's disease, and related dementias) and their combinations were defined using cognitive, motor, and vascular features. Their longitudinal outcome as defined by death and dementia incidence was examined. RESULTS: Preclinical syndromes affected 55.7% (n=299) of subjects. Preclinical syndromes showed a trend for an increased odds of death (odds ratio 1.72, p=0.056) and a significantly increased odds of developing dementia (odds ratio 4.81, p<0.001). Preclinical syndromes were highly sensitive, detecting 52 of 58 (89.7%) incident dementias. Two hundred and sixteen of 268 (80.6%) preclinical subjects did not show dementia over the 3 year period (positive predictive value 19.4%). Subjects defined as having a combination of cognitive, extrapyramidal, and vascular features were at greatest risk of progressing to dementia. CONCLUSIONS: Preclinical syndromes were sensitive and significant predictors of dementia. In view of their poor positive predictive value, the preclinical syndromes as defined in this study remain a research tool needing both definitional refinement and greater periods of observation. Multiple coexistent preclinical disorders resulted in a greater incidence of dementia, providing evidence for an additive role between multiple disorders.  (+info)

Neuropsychiatric aspects of Huntington's disease. (29/634)

OBJECTIVE: Neuropsychiatric symptoms are common in Huntington's disease and have been considered its presenting manifestation. Research characterising these symptoms in Huntington's disease is variable, however, encumbered by limitations within and across studies. Gaining a better understanding of neuropsychiatric symptoms is essential, as these symptoms have implications for disease management, prognosis, and quality of life for patients and caregivers. METHOD: Fifty two patients with Huntington's disease were administered standardised measures of cognition, psychiatric symptoms, and motor abnormalities. Patient caregivers were administered the neuropsychiatric inventory. RESULTS: Ninety eight per cent of the patients exhibited neuropsychiatric symptoms, the most prevalent being dysphoria, agitation, irritability, apathy, and anxiety. Symptoms ranged from mild to severe and were unrelated to dementia and chorea. CONCLUSIONS: Neuropsychiatric symptoms are prevalent in Huntington's disease and are relatively independent of cognitive and motor aspects of the disease. Hypothesised links between neuropsychiatric symptoms of Huntington's disease and frontal-striatal circuitry were explored. Findings indicate that dimensional measures of neuropsychiatric symptoms are essential to capture the full range of pathology in Huntington's disease and are vital to include in a comprehensive assessment of the disease.  (+info)

Relations between hypometabolism in the posterior association neocortex and hippocampal atrophy in Alzheimer's disease: a PET/MRI correlative study. (30/634)

OBJECTIVES: Hippocampal atrophy and hypometabolism in the posterior association neocortex are two well known features of Alzheimer's disease. A correlation between these two features was reported twice previously, suggesting intriguing relations. This question has been reassessed, this time controlling for severity of dementia as well as assessing each side of the brain separately and using a voxel based image analysis in addition to the previously employed regions of interest (ROIs). PATIENTS AND METHODS: Eleven patients were studied with probable Alzheimer's disease and mild to moderate dementia in whom both volume MRI and PET assessed cerebral glucose consumption (CMRGlc) were available. Hypothesis driven correlations between hippocampal width (an index of atrophy) and CMRGlc were performed for two posterior association regions, the superior temporal and the inferior parietal (angular gyrus) cortices, using ROIs set separately for each hemisphere. To confirm significant correlations from the ROIs approach, if any, and to assess their specificity for the posterior association neocortex, CMRGlc image voxel based analysis of correlations with hippocampal width was then carried out. RESULTS: There was a significant correlation, in the positive-neurobiologically expected-direction, between right hippocampal width and right angular gyrus metabolism (p< 0.01, Spearman), which remained significant with Kendall partial correlation controlling for dementia severity (estimated by mini mental state scores). Statistical non-parametric mapping (SnPM) confirmed this correlation (p< 0.025), and showed a single additional correlation in the right middle temporal gyrus (p< 0.005), which is also part of the posterior association cortex. CONCLUSION: The findings with both ROIs and voxel based mapping replicate earlier reports of a relation between hippocampal atrophy and ipsilateral association cortex hypometabolism in Alzheimer's disease, and for the first time document that this relation is both region specific and independent of the dementing process itself. Why the correlation was significant only for the right hemisphere is unclear but may be related to the limited sample. Hippocampal-neocortical disconnection due to early and severe medial temporal lobe pathology may at least partly explain the posterior association cortex hypometabolism found in Alzheimer's disease.  (+info)

ACTIVE: a cognitive intervention trial to promote independence in older adults. (31/634)

The Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) trial is a randomized, controlled, single-masked trial designed to determine whether cognitive training interventions (memory, reasoning, and speed of information processing), which have previously been found to be successful at improving mental abilities under laboratory or small-scale field conditions, can affect cognitively based measures of daily functioning. Enrollment began during 1998; 2-year follow-up will be completed by January 2002. Primary outcomes focus on measures of cognitively demanding everyday functioning, including financial management, food preparation, medication use, and driving. Secondary outcomes include health-related quality of life, mobility, and health-service utilization. Trial participants (n = 2832) are aged 65 and over, and at entry into the trial, did not have significant cognitive, physical, or functional decline. Because of its size and the carefully developed rigor, ACTIVE may serve as a guide for future behavioral medicine trials of this nature.  (+info)

Magnetic resonance imaging of the entorhinal cortex and hippocampus in mild cognitive impairment and Alzheimer's disease. (32/634)

OBJECTIVES: To explore volume changes of the entorhinal cortex (ERC) and hippocampus in mild cognitive impairment (MCI) and Alzheimer's disease (AD) compared with normal cognition (NC); to determine the powers of the ERC and the hippocampus for discrimination between these groups. METHODS: This study included 40 subjects with NC, 36 patients with MCI, and 29 patients with AD. Volumes of the ERC and hippocampus were manually measured based on coronal T1 weighted MR images. Global cerebral changes were assessed using semiautomatic image segmentation. RESULTS: Both ERC and hippocampal volumes were reduced in MCI (ERC 13%, hippocampus 11%, p<0.05) and AD (ERC 39%, hippocampus 27%, p<0.01) compared with NC. Furthermore, AD showed greater volume losses in the ERC than in the hippocampus (p<0.01). In addition, AD and MCI also had cortical grey matter loss (p< 0.01) and ventricular enlargement (p<0.01) when compared with NC. There was a significant correlation between ERC and hippocampal volumes in MCI and AD (both p<0.001), but not in NC. Using ERC and hippocampus together improved discrimination between AD and CN but did not improve discrimination between MCI and NC. The ERC was better than the hippocampus for distinguishing MCI from AD. In addition, loss of cortical grey matter significantly contributed to the hippocampus for discriminating MCI and AD from NC. CONCLUSIONS: Volume reductions in the ERC and hippocampus may be early signs of AD pathology that can be measured using MRI.  (+info)