Working memory and control of attention in persons with Alzheimer's disease and mild cognitive impairment.

The goal of the present study was to assess 3 attentional control processes--divided attention, manipulation capacities, and inhibition--in persons with mild cognitive impairment (MCI) and with mild Alzheimer's disease (AD). Manipulation capacities were tested by comparing immediate serial recall with alphabetical-order recall of words. Divided attention was tested with the Brown-Peterson procedure, in which participants divide their attention between simple addition tasks and consonant trigrams over delays. Inhibition was tested with the Hayling procedure, in which participants complete sentences with words irrelevant to their context. Persons with AD showed severe impairment on the 3 attentional control components. Persons with MCI exhibited impaired performance on the Brown-Peterson procedure but normal performance on the other 2 tasks. With AD and MCI participants, there was a negative correlation between general cognitive deficits and impairment on attentional control tasks, indicating that attentional control deficits increase in the MCI/AD continuum. When separating MCI with and without significant subsequent decline, those with subsequent decline showed impaired performance on both the Brown-Peterson procedure and manipulation task. These data suggest that control of attention tasks can track AD at a preclinical stage and that impairment increases gradually during the preclinical phase of AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Traitement de l'obésité: Soutenir l'individu dans l'appropriation de sa démarche.

Obesity is a serious and prevalent health problem that has numerous negative consequences (World Health Organisation, 1998). Body image dissatisfaction has been recognised as an important psychosocial correlate of obesity. Confronted with the thin-ideal model promoted by our society, most overweight or obese women are preoccupied with their body and want to lose excess weight in order to reduce the gap between their actual and desired weight. They also strive to attain this thin-ideal but unreachable model. Although, the underpinnings of obesity are quite clear (i.e., a discrepancy between energy intake and energy expenditure) its treatment is far more complicated. Treatments of obesity, relying essentially on reducing calorie intake while increasing physical activity, seem to be effective in terms of initial weight loss but are often ineffective in terms of long-term maintenance. It is important to identify the potential psychosocial factors that might be involved in the explanation of maintenance failure. This article, discusses obesity and reviews the traditional treatments and their efficacy. The article outlines, based on Self-Determination Theory (SDT), a clinical conceptualisation of maintenance failure. Self-determination has been widely used as a theoretical framework for understanding behavioural change. Recently, empirical findings have supported the relevance of SDT in the comprehension of weight problems. Pelletier and his colleagues (2004) have shown that self-determination is negatively associated with the endorsement of sociocultural pressures to be thin, body dissatisfaction and bulimic symptoms. In addition, they demonstrated that women presenting a self-determined regulation of their alimentation (as compared to women whose regulation is not self-determined) are more preoccupied with the quality of their food than with its quantity, perceive themselves as self-efficient in the regulation their alimentation, engage in more healthful eating behaviours and manifest better psychological functioning. Concurrently, some studies have shown that self-determination is linked to treatment adherence, quantity of weight loss and maintenance. These results clearly indicate the importance of relying not only on the intensity of motivation but also on examining the nature of that motivation in order to understand weight loss and maintenance. Moreover, the distinction between intensity and nature of motivation must be taken into account in our clinical explanation of maintenance failures. Furthermore, although autonomy-support is an essential component of SDT, up until now studies on SDT have been conducted in intensive weight loss programs, programs that are not optimizing autonomy-support. This situation shows an important gap between theory and practice. In reference to a new paradigm of weight management (health at every size approach), our article encourages the development of interventions that will promote autonomy-support and suggests a more extensive participation of psychologists in the development and the empirical validation of such interventions. We conclude with some guidelines to promote autonomy-support in weight management interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for gist and detail information in Alzheimer's disease and mild cognitive impairment.

Two experiments examined different forms of gist and detail memory in people with Alzheimer's disease (AD) and those with amnestic mild cognitive impairment (MCI). In Experiment 1, 14 AD, 14 MCI, and 22 control participants were assessed with the Deese-Roediger-McDermott paradigm. Results indicated that false recognition of nonstudied critical lures (gist memory) was diminished in the AD compared with the MCI and control groups; the two latter cohorts performed similarly. In Experiment 2, 14 AD, 20 MCI, and 26 control participants were tested on a text memory task. Results revealed that recall of both macropropositions (gist information) and micropropositions (detail information) decreased significantly in AD and in MCI as compared with control participants. This experiment also revealed that the impairment was comparable between gist and detail memory. In summary, the results were consistent across experiments in the AD but not in the MCI participants. The discrepancy in MCI participants might be explained by differences in the degree of sensitivity of the experimental procedures and/or by the differences in the cognitive processes these procedures assessed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic Segmentation of the Left Ventricle in Cardiac MR and CT Images

This paper describes a segmentation technique to automatically extract the myocardium in 4D cardiac MR and CT datasets. The segmentation algorithm is a two step process. The global localization step roughly localizes the left ventricle using techniques such as maximum discrimination, thresholding and connected component analysis. The local deformations step combines EM-based region segmentation and Dijkstra active contours using graph cuts, spline fitting, or point pattern matching. The technique has been tested on a large number of patients and both quantitative and qualitative results are presented.     

Assessment of semantic processing in patients with Alzheimer's type dementia: The release-of-proactive-inhibition paradigm.

Investigated memory functioning in 10 patients with dementia of Alzheimer's type (DAT [aged 54–87 yrs]) and 20 age-matched normal controls (CTLs) by using the release-from-proactive-interference paradigm. DAT Ss exhibited lower correct recall and higher intrusion rates than did CTLs. DAT Ss did not show the expected build-up and release from proactive interference when correct recall was considered but showed the expected pattern when intrusion rate was considered. CTLs showed evidence of semantic processing on both measures. Results are discussed in relation to the defects in semantic memory hypothesized in Alzheimer's disease. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Viscoelastic properties of acrylonitrile-butadiene-styrene (ABS) polymers in the molten state

The viscoelastic behavior of acrylonitrile-butadiene-styrene (ABS) terpolymers is studied in the molten state. First, the behavior of the styrene-acrylonitrile (SAN) matrix is determined. Then, the effect of the degree of grafting on ABS rheological properties is emphasized. A critical degree of grafting (DGc), corresponding to a minimum of the viscoelastic functions in the low frequency region, is determined. It defines a critical thickness of the grafted layer, and is related to the conformation of the grafted chains at the surface of the rubber particle. The DGc affects the morphology of the ABS and also affects the appearance of a secondary plateau at low frequencies. The effects of the rubber particles, of the grafted chains, and of the morphology on the appearance of the secondary plateau at low frequencies are clearly dissociated.     

Critical multiple angiogenic factors secreted by glioblastoma stem-like cells underline the need for combinatorial anti-angiogenic therapeutic strategies

Glioblastomas are the most frequent adult primary brain tumors that still remain fatal despite major clinical efforts. As in other solid tumors, populations of glioblastoma stem-like cells (GSCs) endowed with tumor initiating and therapeutic resistance properties have been identified. Glioblastomas are highly vascularized tumors resulting in a rich dialog between GSCs and endothelial cells. In one direction, endothelial cells and their secreted proteins are able to sustain GSC properties while, in turn, GSCs can promote neoangiogenesis, modulate endothelial cell functions and may even transdifferentiate into endothelial cells. Accordingly, targeting tumor vasculature seems a promising issue despite incomplete and transient results obtained from anti-vascular endothelial growth factor therapeutic trials. Recent findings of novel GSC-secreted molecules with pro-angiogenic properties (Semaphorin 3A, hepatoma-derived growth factor) open the path to the design of a concerted attack of glioblastoma vasculature that could overcome the development of resistance to single-targeted therapies while keeping away the toxicity of the treatments.     

Completing codes in a sofic shift

We define a code in a sofic shift as a set of blocks of symbols of the shift such that any block of the shift has at most one decomposition into code words. It is maximal if it is not strictly included in another one. Such a code is complete in the sofic shift if any block of the shift occurs within some concatenation of code words. We prove that a maximal code in an irreducible sofic shift is complete in this shift. We give an explicit construction of a regular completion of a regular code in a sofic shift. This extends the well known result of Ehrenfeucht and Rozenberg to the case of codes in sofic systems. We also give a combinatorial proof of a result concerning the polynomial of a code in a sofic shift.     

Hypnotic discontinuation in chronic insomnia: Impact of psychological distress, readiness to change, and self-efficacy.

Objective: To compare individuals who were successful in discontinuing hypnotic medications against those who were not on measures of insomnia severity, medication withdrawal symptoms, psychological symptoms, perceived health, readiness to change and self-efficacy. Design: Secondary analyses of a randomized clinical trial comparing a hypnotic taper intervention with or without self-help treatment for insomnia. Main Outcome Measures: Self-report measures of insomnia severity, medication withdrawal symptoms, depression and anxiety symptoms, physical and mental health, stages of change, readiness to change, decisional balance, and general and situational self-efficacy. Results: There were no significant differences at baseline between medication-free individuals and those still using sleep medication at the end of a taper intervention. Group differences emerged midway through the 8-week withdrawal program and were accentuated after the intervention; participants who remained medication-free during the next six months had less severe insomnia and anxiety symptoms, a more positive perception of their health and higher self-efficacy to refrain from hypnotic use in various situations. Contrary to expectations, there were no differences between drug-free and nondrug-free participants on both readiness to change and stages of change. Conclusions: Chronic users of hypnotic medications entered a taper intervention with equal levels of psychological distress, health, self-efficacy, and readiness to change. Successful hypnotic discontinuation was associated with overall improvement of insomnia, anxiety and distress symptoms, perceived health and self-efficacy. More intensive and individualized therapeutic attention may be warranted for individuals experiencing worsening of insomnia symptoms, more withdrawal symptoms and psychological distress, and lower self-efficacy during medication discontinuation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)