An evaluation of volume-based morphometry for prediction of mild cognitive impairment and Alzheimer's disease.

Voxel-based morphometry from conventional T1-weighted images has proved effective to quantify Alzheimer's disease (AD) related brain atrophy and to enable fairly accurate automated classification of AD patients, mild cognitive impaired patients (MCI) and elderly controls. Little is known, however, about the classification power of volume-based morphometry, where features of interest consist of a few brain structure volumes (e.g. hippocampi, lobes, ventricles) as opposed to hundreds of thousands of voxel-wise gray matter concentrations. In this work, we experimentally evaluate two distinct volume-based morphometry algorithms (FreeSurfer and an in-house algorithm called MorphoBox) for automatic disease classification on a standardized data set from the Alzheimer's Disease Neuroimaging Initiative. Results indicate that both algorithms achieve classification accuracy comparable to the conventional whole-brain voxel-based morphometry pipeline using SPM for AD vs elderly controls and MCI vs controls, and higher accuracy for classification of AD vs MCI and early vs late AD converters, thereby demonstrating the potential of volume-based morphometry to assist diagnosis of mild cognitive impairment and Alzheimer's disease.

Individual prediction of cognitive decline in mild cognitive impairment using support vector machine-based analysis of diffusion tensor imaging data.

Although cross-sectional diffusion tensor imaging (DTI) studies revealed significant white matter changes in mild cognitive impairment (MCI), the utility of this technique in predicting further cognitive decline is debated. Thirty-five healthy controls (HC) and 67 MCI subjects with DTI baseline data were neuropsychologically assessed at one year. Among them, there were 40 stable (sMCI; 9 single domain amnestic, 7 single domain frontal, 24 multiple domain) and 27 were progressive (pMCI; 7 single domain amnestic, 4 single domain frontal, 16 multiple domain). Fractional anisotropy (FA) and longitudinal, radial, and mean diffusivity were measured using Tract-Based Spatial Statistics. Statistics included group comparisons and individual classification of MCI cases using support vector machines (SVM). FA was significantly higher in HC compared to MCI in a distributed network including the ventral part of the corpus callosum, right temporal and frontal pathways. There were no significant group-level differences between sMCI versus pMCI or between MCI subtypes after correction for multiple comparisons. However, SVM analysis allowed for an individual classification with accuracies up to 91.4% (HC versus MCI) and 98.4% (sMCI versus pMCI). When considering the MCI subgroups separately, the minimum SVM classification accuracy for stable versus progressive cognitive decline was 97.5% in the multiple domain MCI group. SVM analysis of DTI data provided highly accurate individual classification of stable versus progressive MCI regardless of MCI subtype, indicating that this method may become an easily applicable tool for early individual detection of MCI subjects evolving to dementia.

Cognitive behavioural therapy for obesity and binge eating associated to antipsychotic drugs

Background and Aims: Overweight, obesity and binge eating disorder are commonly reported in persons with severe mental disorders. Particularly, antipsychotic drugs (AP) induce weight gain in up to half of the patients. The aim of the present study is to confirm a previous study results on a larger sample of patients, to assess the impact of the interventions on other relevant dimensions of eating and weight related cognitions as well as to assess potential clinical indicators of outcomes such as AP drug, concomitant treatment with lithium or carbamazepine, psychiatric diagnostic, binge eating and severity of cognitive distortions. Method: A controlled study (12-week CBT vs. B N E) was carried out on 99 patients treated with an AP and who have gained weight following this treatment. Binge eating symptomatology, eating and weight-related cognitions, as well as weight and body mass index were assessed before treatment, at 12 weeks and at 24 weeks. Results: The findings confirms usefulness and effectiveness of the proposed CBT program on the treatment of binge symptomatology, cognitive distortions and obesity in patients treated with AP. Reduction of binge symptoms and maladapted cognitions appeared early, whereas the effect on weight appeared later during the follow up observation. No differences on outcomes were found across pharmacotherapy characteristics, diagnostic categories, binge eating nor severity of cognitive distortions. Conclusion: The proposed CBT treatment is useful for patients suffering from weight gain associated with AP treatments indeed when a concomitant treatment with lithium or valproate was given.

Evaluation of errors in alpine skiing video analysis

INTRODUCTION: Video records are widely used to analyze performance in alpine skiing at professional or amateur level. Parts of these analyses require the labeling of some movements (i.e. determining when specific events occur). If differences among coaches and differences for the same coach between different dates are expected, they have never been quantified. Moreover, knowing these differences is essential to determine which parameters reliable should be used. This study aimed to quantify the precision and the repeatability for alpine skiing coaches of various levels, as it is done in other fields (Koo et al, 2005). METHODS: A software similar to commercialized products was designed to allow video analyses. 15 coaches divided into 3 groups (5 amateur coaches (G1), 5 professional instructors (G2) and 5 semi-professional coaches (G3)) were enrolled. They were asked to label 15 timing parameters (TP) according to the Swiss ski manual (Terribilini et al, 2001) for each curve. TP included phases (initiation, steering I-II), body and ski movements (e.g. rotation, weighting, extension, balance). Three video sequences sampled at 25 Hz were used and one curve per video was labeled. The first video was used to familiarize the analyzer to the software. The two other videos, corresponding to slalom and giant slalom, were considered for the analysis. G1 realized twice the analysis (A1 and A2) at different dates and TP were randomized between both analyses. Reference TP were considered as the median of G2 and G3 at A1. The precision was defined as the RMS difference between individual TP and reference TP, whereas the repeatability was calculated as the RMS difference between individual TP at A1 and at A2. RESULTS AND DISCUSSION: For G1, G2 and G3, a precision of +/-5.6 frames, +/-3.0 and +/-2.0 frames, was respectively obtained. These results showed that G2 was more precise than G1, and G3 more precise than G2, were in accordance with group levels. The repeatability for G1 was +/-3.1 frames. Furthermore, differences among TP precision were observed, considering G2 and G3, with largest differences of +/-5.9 frames for "body counter rotation movement in steering phase II", and of 0.8 frame for "ski unweighting in initiation phase". CONCLUSION: This study quantified coach ability to label video in term of precision and repeatability. The best precision was obtained for G3 and was of +/-0.08s, which corresponds to +/-6.5% of the curve cycle. Regarding the repeatability, we obtained a result of +/-0.12s for G1, corresponding to +/-12% of the curve cycle. The repeatability of G2 and G3 are expected to be lower than the precision of G1 and the corresponding repeatability will be assessed soon. In conclusion, our results indicate that the labeling of video records is reliable for some TP, whereas caution is required for others. REFERENCES Koo S, Gold MD, Andriacchi TP. (2005). Osteoarthritis, 13, 782-789. Terribilini M, et al. (2001). Swiss Ski manual, 29-46. IASS, Lucerne.

On the relationship between performance-approach goals and cognitive performance : when the desire to outperform others becomes interfering

Cette thèse explore dans quelle mesure la poursuite d'un but de performance-approche (i.e., le désir de surpasser autrui et de démontrer ses compétences) favorise, ou au contraire endommage, la réussite et l'apprentissage-une question toujours largement débattue dans la littérature. Quatre études menées en laboratoire ont confirmé cette hypothèse et démontré que la poursuite du but de performance-approche amène les individus à diviser leur attention entre d'une part la réalisation de la tâche évaluée, et d'autre part la gestion de préoccupations liées à l'atteinte du but-ceci empêchant une concentration efficace sur les processus de résolution de la tâche. Dans une deuxième ligne de recherche, nous avons ensuite démontré que cette distraction est exacerbée chez les individus les plus performants et ayant le plus l'habitude de réussir, ceci dérivant d'une pression supplémentaire liée au souhait de maintenir le statut positif de « bon élève ». Enfin, notre troisième ligne de recherche a cherché à réconcilier ces résultats-pointant l'aspect distractif du but de performance-approche-avec le profil se dégageant des études longitudinales rapportées dans la littérature-associant ce but avec la réussite académique. Ainsi, nous avons mené une étude longitudinale testant si l'adoption du but de performance-approche en classe pourrait augmenter la mise en oeuvre de stratégies d'étude tactiquement dirigées vers la performance-favorisant une réussite optimale aux tests. Nos résultats ont apporté des éléments en faveur de cette hypothèse, mais uniquement chez les élèves de bas niveau. Ainsi, l'ensemble de nos résultats permet de mettre en lumière les processus cognitifs à l'oeuvre lors de la poursuite du but de performance-approche, ainsi que d'alimenter le débat concernant leur aspect bénéfique ou nuisible en contexte éducatif. -- In this dissertation, we propose to investigate whether the pursuit of performance-approach goals (i.e., the desire to outperform others and appear talented) facilitates or rather endangers achievement and learning-an issue that is still widely discussed in the achievement goal literature. Four experiments carried out in a laboratory setting have provided evidence that performance- approach goals create a divided-attention situation that leads cognitive resources to be divided between task processing and the activation of goal-attainment concerns-which jeopardizes full cognitive immersion in the task. Then, in a second research line, we found evidence that high- achievers (i.e., those individuals who are the most used to succeed) experience, under evaluative contexts, heightened pressure to excel at the task, deriving from concerns associated with the preservation of their "high-achiever" status. Finally, a third research line was designed to try to reconcile results stemming from our laboratory studies with the overall profile emerging from longitudinal research-which have consistently found performance-approach goals to be a positive predictor of students' test scores. We thus set up a longitudinal study so as to test whether students' adoption of performance-approach goals in a long-term classroom setting enhances the implementation of strategic study behaviors tactically directed toward goal-attainment, hence favoring test performance. Our findings brought support for this hypothesis, but only for low-achieving students. Taken together, our findings shed new light on the cognitive processes at play during the pursuit of performance-approach goals, and are likely to fuel the debate regarding whether performance-approach goals should be encouraged or not in educational settings.

A Randomized Controlled Trial of the Effectiveness of Computer-Assisted Cognitive Remediation (CACR) in Adolescents with Psychosis or at High Risk of Psychosis.

Background: Computer assisted cognitive remediation (CACR) was demonstrated to be efficient in improving cognitive deficits in adults with psychosis. However, scarce studies explored the outcome of CACR in adolescents with psychosis or at high risk. Aims: To investigate the effectiveness of a computer-assisted cognitive remediation (CACR) program in adolescents with psychosis or at high risk. Method: Intention to treat analyses included 32 adolescents who participated in a blinded 8-week randomized controlled trial of CACR treatment compared to computer games (CG). Cognitive abilities, symptoms and psychosocial functioning were assessed at baseline and posttreatment. Results: Improvement in visuospatial abilities was significantly greater in the CACR group than in CG. Other cognitive functions, psychotic symptoms and psychosocial functioning improved significantly, but at similar rates, in the two groups. Conclusion: CACR can be successfully administered in this population; it proved to be effective over and above CG for the most intensively trained cognitive ability.

Effects of cognitive abilities on metapopulation connectivity

Connectivity among demes in a metapopulation depends on both the landscape's and the focal organism's properties (including its mobility and cognitive abilities). Using individual-based simulations, we contrast the consequences of three different cognitive strategies on several measures of metapopulation connectivity. Model animals search suitable habitat patches while dispersing through a model landscape made of cells varying in size, shape, attractiveness and friction. In the blind strategy, the next cell is chosen randomly among the adjacent ones. In the near-sighted strategy, the choice depends on the relative attractiveness of these adjacent cells. In the far-sighted strategy, animals may additionally target suitable patches that appear within their perceptual range. Simulations show that the blind strategy provides the best overall connectivity, and results in balanced dispersal. The near-sighted strategy traps animals into corridors that reduce the number of potential targets, thereby fragmenting metapopulations in several local clusters of demes, and inducing sink-source dynamics. This sort of local trapping is somewhat prevented in the far-sighted strategy. The colonization success of strategies depends highly on initial energy reserves: blind does best when energy is high, near-sighted wins at intermediate levels, and far-sighted outcompetes its rivals at low energy reserves. We also expect strong effects in terms of metapopulation genetics: the blind strategy generates a migrant-pool mode of dispersal that should erase local structures. By contrast, near- and far-sighted strategies generate a propagule-pool mode of dispersal and source-sink behavior that should boost structures (high genetic variance among- and low variance within local clusters of demes), particularly if metapopulation dynamics is also affected by extinction-colonization processes. Our results thus point to important effects of the cognitive ability of dispersers on the connectivity, dynamics and genetics of metapopulations.