Facteur de risque | EPFL Graph Search

Un facteur de risque est une source de risque qui indique un certain degré de causalité, supérieur à une simple corrélation, avec un risque. Terminologie Un facteur de risque doit en principe être contrôlable, c'est-à-dire que l'on peut avoir une influence sur ce facteur. Il est important de distinguer un « facteur de risque » d'un « marqueur de risque » : dans le premier cas, le « facteur », mis en évidence d'une manière ou d'une autre, est partiellement responsable du risque. Maîtriser ce facteur revient donc à diminuer significativement ce dernier. Dans le cas d'un marqueur de risque, il existe une simple corrélation entre le et le risque et diminuer artificiellement ce marqueur ne change en rien le risque final. Cette distinction est parfois subtile, puisque être du sexe masculin est un facteur de risque reconnu de l'infarctus du myocarde alors qu'il est difficilement envisageable de changer de sexe pour cette raison. L'identification du facteur de risque est souve

Multidrug-resistant tuberculosis: household transmission and associated risk factors

Laurence Läser

Given the global burden of tuberculosis, and more precisely of multidrug-resistant (MDR) tuberculosis (TB), one of the most pressing epidemiological issues is the study and prevention of transmission. The study aims to assess transmission within households that present at least two cases of MDR-TB and the possible risk factors, from MDR-TB isolates collected in Lima, Peru and further characterized by genotyping methods, spoligotyping and mycobacterial interspersed repetitive units (MIRU) - variable number tandem repeat (VNTR), used for DNA fingerprinting. Apart from the genotyping results, the data set also provides the drug susceptibility testing (DST) profile for each isolate, as well as information on the households and the patients. The key assumption to transform molecular data into epidemiological data is that all identical isolates are classified in the same cluster, the cluster belong to a unique strain of tuberculosis, and a unique strain infecting more than one individual is presumed to be the result of direct transmission. The analysis is divided in two parts, first the establishment of household transmission or outside transmission for each isolate and then the following epidemiological analysis; and requires the use of Matlab and Stata software. The main results are the cohort characteristics, the concordance between the two genotyping methods, the clusters' composition and size frequency, the transmission analysis, the amplification of resistance analysis and the risk factors analysis for household transmission. From there, the main findings are the high rate of household transmission (more than 80%) of the isolates and drug resistance amplification (up to 10 new resisitances within one household clustered strain). The risk factor analysis did not present any significant results, but a few trends that are worth to explore in the future

2010

Impaired cognitive flexibility and heightened urgency are associated with increased alcohol consumption in rodent models of excessive drinking

Emanuela De Falco

Alcohol use disorder (AUD) is characterized by impairments in decision-making that can exist as stable traits or transient states. Cognitive inflexibility reflects an inability to update information that guides decision-making and is thought to contribute to the inability to abstain from drinking. While several studies have reported evidence of impaired cognitive flexibility following chronic alcohol exposure, evidence that a pre-existing impairment in cognitive flexibility is a heritable risk factor for AUD is scarce. Here, we found that cognitive flexibility was impaired in rodents selectively bred for excessive alcohol consumption (alcohol preferring (P) rats), on the attentional set-shifting task (ASST). Further, the degree of impairment is predictive of future ethanol consumption, thus suggesting that cognitive inflexibility is a stable trait capable of predisposing one for drinking. In a second set of experiments, we observed an impairment in the ability of P rats to use a previously learned rule to guide foraging in a simple discrimination task. Convergence across several behavioral measures suggested that this impairment reflected a state of heightened urgency that interfered with decision-making. A similar impairment on a simple discrimination task was observed in Wistar rats with a history of alcohol consumption. These findings indicate how trait and state variables-in this case, impaired cognitive flexibility and heightened urgency, respectively-may influence the risk for excessive drinking. Furthermore, our results suggest that cognitive inflexibility and urgency can exist as both risk factors for and the result of alcohol exposure.

WILEY2021

The aging brain as a model to understand motor skill acquisition in humans and its restoration using non-invasive brain stimulation

Pablo Maceira Elvira

Motor skill acquisition is essential to our survival, as it enables an efficient interaction with the changing world around us. The acquisition of novel sequential tasks, of particular relevance due to their pervasiveness in everyday life activities, can become more challenging at an advanced age, with structural and functional changes in the brain often resulting in diminished learning abilities. During the pursuit of my doctoral degree, I studied some of the processes leading to the acquisition of a novel sequential motor task, and how some of the mechanisms underlying these processes differ between healthy young and older adults. Young adults acquired the sequential task effectively by prioritizing its accurate execution early in training and focusing on increasing their speed thereafter, resulting in the generation of mechanically efficient execution patterns in the replication of the sequence. In contrast, older adults improved both the accuracy and the speed simultaneously and gradually after more extensive practice, which resulted in an overall decreased performance of the task. However, anodal direct current stimulation applied over the motor cortex partially restored skill acquisition in older adults by facilitating the early improvement of the accuracy, enabling an accelerated generation of efficient execution patterns in the sequence, similar to those seen in young adults. Further investigations into the effects of stimulation to improve skill acquisition in healthy older adults showed age not to be a determinant factor for an individual's proneness to benefit from stimulation; rather, it is the state of the neural system of each individual what likely determines the potential benefits to be had from stimulation. Therefore, a better understanding of the mechanisms targeted by stimulation and the identification of parameters signaling an individual's likelihood to benefit from it are needed to use these techniques to their full potential. Leveraging this knowledge and taking advantage of the portability, robustness and accessibility of this technique could represent an attractive option for applications involving extensive motor training, such as rehabilitative training provided after stroke.

EPFL2022

The aging brain as a model to understand motor skill acquisition in humans and its restoration using non-invasive brain stimulation

Pablo Maceira Elvira

EPFL2022