The cardiovascular hemodynamic responses to various levels of orthostatic stress in children

The ability of the cardiovascular system to quickly and efficiently adapt to an orthostatic stress is vital for the human body to function on earth. The way in which the various aspects of the cardiovascular system work together to counteract an orthostatic stress has been previously quantified in the adult population. However, there are still many unknowns surrounding the topic of how the cardiovascular system functions to cope with this same stress in children. The purpose of this study was to describe the cardiovascular hemodynamic adaptations to various levels of orthostatic stress induced using a lower body negative pressure (LBNP) chamber in pre-pubertal boys. A secondary purpose was to determine indices of baroreceptor sensitivity (BRS) at both rest and during low levels of LBNP in this same pediatric sample. Finally, this study aimed to compare the relative responses to LBNP between the children and adults. To complete the study 20 healthy pre-pubertal boys and adult males (9.3 ± 1.1 and 23 ± 1.8 years of age respectively) were recruited and randomly exposed to three levels of LBNP (15, 20 and 25 mmHg). At rest and during the application of the LBNP heart rate (HR), manual and bcat-by-beat systolic (SBP), diastolic (DBP) and mean arterial blood pressure (MAP) were monitored continuously. Aortic diameter was measured at rest and peak aortic blood velocity (PV) was recorded continuously for at least I minute during each baseline and LBNP condition. From the raw data HR, stroke volume (SV), cardiac output (Q), total peripheral resistance (TPR), low frequency baroreceptor sensitivity (LF BRS), high frequency baroreceptor sensitivity (HF BRS) and LFIIIF ratio were calculated. At rest, llR wa'i higher and SBP, SV, Q and LF/HF ratio were lower in the children compared to the adult males (pgJ.05). In response to the increasing LEN!> IIR and TPR increased, and LF BRS. SV and Q decreased in the adult group (pSf).05). while the same levels of LBNP caused an increase in TPR and a decrease in SBP, SV and Q in the children (pSf).05). Although not significant, the LF/HF ratio in the adult group showed an increasing trend in response to increased negative pressure (p=O.088). As for resting BRS, there were no significant differences in LF or HF BRS between the children and the adults despite a tendency for both measures to be 18% lower in the children. Also the LF/HF ratio was almost significantly greater in the adults compared to the children (p=O.057). In addition, a comparison between the relative adult and child responses to LBNP yielded no significant group by level interactions. This result should be taken with caution though, as the low sample size and high measurement variability generated very low statistical power for this analysis. In conclusion, the results of this study suggest that the hemodynamic adaptations to an orthostatic stress were less pronounced in the prepubertal males, most likely due to an underdeveloped autonomic system. These results need to be strengthened by further research before any implications can be derived for health care purposes.

The role of physical activity and perceived adequacy on cardiorespiratory fitness in children with developmental coordination disorder

Evidence suggests that children with developmental coordination disorder (DCD) have lower levels of cardiorespiratory fitness (CRF) compared to children without the condition. However, these studies were restricted to field-based methods in order to predict V02 peak in the determination of CRF. Such field tests have been criticised for their ability to provide a valid prediction of V02 peak and vulnerability to psychological aspects in children with DCD, such as low perceived adequacy toward physical activity. Moreover, the contribution of physical activity to the variance in V02 peak between the two groups is unknown. The purpose of our study was to determine the mediating role of physical activity and perceived adequacy towards physical activity on V02 peak in children with significant motor impairments. This prospective case-control design involved 122 (age 12-13 years) children with significant motor impairments (n=61) and healthy matched controls (n=61) based on age, gender and school location. Participants had been previously assessed for motor proficiency and classified as a probable DCD (p-DCD) or healthy control using the movement ABC test. V02 peak was measured by a progressive exercise test on a cycle ergometer. Perceived adequacy was measured using a 7 -item subscale from Children's Selfperception of Adequacy and Predilection for Physical Activity scale. Physical activity was monitored for seven days with the Actical® accelerometer. Children with p-DCD had significantly lower V02 peak (48.76±7.2 ml/ffm/min; p:50.05) compared to controls (53.12±8.2 ml/ffm/min), even after correcting for fat free mass. Regression analysis demonstrated that perceived adequacy and physical activity were significant mediators in the relationship between p-DCD and V02 peak. In conclusion, using a stringent laboratory assessment, the results of the current study verify the findings of earlier studies, adding low CRF to the list of health consequences associated with DCD. It seems that when testing for CRF in this population, there is a need to consider the psychological barriers associated with their condition. Moreover, strategies to increase physical activity in children with DCD may result in improvement in their CRF.

Left ventricular structure in children with developmental coordination disorder

Developmental coordination disorder (p-DCD) is a neuro-developmental disorder featuring impairment in developing motor coordination. This study examined left ventricular mass (LVM) in children with p-DCD (n=63) and controls (n=63). LVM was measured using echocardiography. Body composition was determined using BOD POD and peak oxygen uptake (peak V02) was measured by a progressive exercise test. Height, weight and blood pressure were also measured. LVM was not significantly elevated in p-DCD compared to controls. Peak V02 was lower and SBP, BMI, HR, and BF(%) were significantly higher in p-DCD. They also demonstrated elevated stroke volume (SV), cardiac output (CO), end-diastolic volume, and ventricular diameter in diastole. In regression analyses, p-DCD was a significant predictor of SV and CO after accounting for height, FFM, V02FFM, and sex. These differences in children with p-DCD indicate obesity related changes in the left ventricle and may represent early stages of developing hypertrophy of the left ventricle.

Physical Activity and Fitness in Children with Developmental Disorder

Introduction: Developmental coordination disorder (DCD) is a prevalent condition characterized by poor motor proficiency that interferes with a child‟s activities of daily living. Children with DCD often experience compromised health-related fitness components such as cardiorespiratory fitness (CRF). Purpose: To better understand the physical activity and fitness characteristics of children with probable DCD (pDCD), with a particular focus on CRF. Specifically: (1) to present a synopsis of current literature; (2) to determine the longitudinal trajectories of CRF; (3) to compare the submaximal CRF of children with and without pDCD. Methods: A comprehensive, systematic literature review was conducted of the recent available data on fitness and physical activity and pDCD (Chapter 2). This review provided the background for the other two studies included in this thesis. In Chapter 3, a prospective cohort design was used to assess how CRF in children with pDCD changes over time (56 months) relative to a group of typically developing controls. Using a nested-case control design, 63 subjects with pDCD and 63 matched controls from the larger sample were recruited to participate in the lab-based component of the study (Chapter 4). In this investigation CRF was examined using the oxygen cost of work (VO2) during an incremental test on a cycle ergometer. Results: The literature review showed that fitness parameters, including CRF and physical activity levels, were consistently reduced in children with pDCD. Chapter 3 demonstrated that the difference in CRF between children with pDCD and typically developing children is substantial, and that it tends to increase over time. Results from VO2 assessments showed that children with pDCD utilized more oxygen to sustain the same submaximal workloads compared to typically developing children. Conclusions: Findings from this thesis have made several important contributions to our understanding of children with pDCD. Since differences in CRF between children with and without pDCD tend to worsen over time, this adds to the argument that interventions intended to improve CRF may be appropriate for children with motor difficulties. This thesis also presented the first evidence suggesting that DCD involves higher energy expenditure, and could help explain why children with pDCD perform poorly on tasks requiring CRF.

ARTERIAL STIFFNESS IN CHILDREN WITH AND WITHOUT DEVELOPMENTAL COORDINATION DISORDER

The purpose of this study was to determine whether children with potential developmental coordination disorder (p-DCD) demonstrate increased arterial stiffness and thickness compared to age and school matched controls (mean age 14.7 yrs). We also assessed whether these measures differed by sex. Compliance, distensibility, and intima-media thickness (IMT) were measured at the common carotid artery for 28 children with p-DCD and 47 controls. ECG-R-wave-toe pulse wave velocity (PWV) was also measured for 29 children with p-DCD and 45 controls. We found that compared to controls males with p-DCD had significantly higher PWV (3.8±0.2 vs. 4.1±0.3, p=0.001) and lower distensibility (0.82± 0.19 vs. 0.70± 0.17, p=0.034) while females showed no significant differences (p=0.523 and p=0.123 respectively). As a result, it is apparent that sex differences exist with respect to arterial health within this population and that children with p-DCD may be more likely to develop cardiovascular disease later in life.

The Association of Energy Intake with Body Mass in Children With and Without Probable Developmental Coordination Disorder

Objective To determine if there is an association between energy intake (EI) and overweight or obesity status (OWOB) in children with and without probable developmental coordination disorder (p-DCD). Methods 1905 children were included. The Bruininks-Oseretsky Test of Motor Proficiency was used to assess p-DCD, body mass index for OWOB, and the Harvard Food Frequency Questionnaire for EI. Comparative tests and logistic regressions were performed. Results Reported EI was similar between p-DCD and non-DCD children among boys (2291 vs. 2281 kcal/day, p=0.917), but much lower in p-DCD compared to non-DCD girls (1745 vs.. 2068 kcal/day, p=0.007). EI was negatively associated with OWOB in girls only (OR: 0.82 (0.68, 0.98)). Conclusions Girls with p-DCD have a lower reported EI compared to their non-DCD peers. EI is negatively associated with OWOB in girls with p-DCD. Future research is needed to assess longitudinally the potential impact of EI on OWOB in this population.

Autonomic Cardiovascular Control in Children and Adolescents

This thesis investigated the impact of pubertal maturation and sex on cardiovagal baroreflex sensitivity (BRS) and arterial properties of the common carotid artery (CCA), and the relationship between CCA arterial properties and BRS. This thesis also investigated the effect of orthostatic stress on arterial properties of the CCA and carotid sinus (CS), as well as their impact on BRS in response to orthostatic stress. Children and adolescents between the ages of 8-18 years were examined. To assess pubertal maturation participants were organized into five pubertal groups based on the criteria of Tanner. BRS was assessed by transfer function analysis in the low frequency range (0.05 – 0.15Hz). Pulse pressure (PP) was measured at the CCA (PPCCA) and CS (PPCS) using applanation tonometry, and at the finger (PPFinger) using photoplethysmography. Ultrasound sonography and applanation tonometry were used to determine the distensibility coefficient (DC) at the CCA (DCCCA) and CS (DCCS). A moderate posture stimulus was implemented by passively moving participants into a 50° seated-recumbent (SR) position. The results demonstrated a sex-by-maturation interaction on BRS (p= 0.019). BRS decreased from early- to post-puberty in males (p<0.01), and remained unchanged in females. Females demonstrated greater BRS compared to males post-puberty (p<0.05). CCA distensibility was not affected by sex or maturation and was not related to BRS. PPCS was greater than PPCCA (p<0.001), while PPFinger was greater than both PPCCA (p<0.001) and PPCS (p<0.001). In response to SR, the relative change in PPFinger was significantly different than the relative change in PPCCA (p<0.001) and PPCS (p<0.001), while the relative change between PPCCA and PPCS were not different. Finally, in response to SR there was a significant decrease in DCCS (p=0.001), but not DCCCA. The relative change in BRS in response to SR was significantly correlated to the relative change in DCCS (p=0.004), but not DCCCA. The findings demonstrated an important sex-dependent maturation effect on BRS in children and adolescents that was not explained by CCA distensibility. Also, the CS and CCA responded differently to orthostatic stress. The CS was more suitable to evaluate the effect of arterial distensibility on BRS in response to posture change.

La comorbidité chez les joueurs pathologiques en traitement

Plusieurs études telles que le NESARC ont démontré la comorbidité chez les joueurs pathologiques dans la population générale et dans des échantillons cliniques. Le jeu pathologique se présente souvent avec des troubles comorbides tels que les toxicomanies, les troubles de l’humeur, les troubles anxieux et les troubles de la personnalité. Cette étude a été réalisée auprès de 40 joueurs pathologiques admis en traitement au Centre Dollard-Cormier, Institut universitaire sur les dépendances à Montréal. Les objectifs étaient d’évaluer : la consommation d’alcool et de drogues, la présence d’une détresse psychologique caractérisée par des symptômes et des syndromes cliniques ainsi que par des troubles de la personnalité et la prévalence du trouble de l’ÉSPT dans l’échantillon. L’ICJE a été utilisé pour évaluer la gravité du jeu. Les autres troubles ont été mesurés à travers l’IGT, l’AUDIT, le MCMI-III, le QÉT et l’ÉMST. Les résultats montrent que 65 % des participants présentent une consommation problématique d’alcool (25 % actuellement, 40 % dans le passé), 27,5 % une consommation problématique de drogues; 52,5 %, un diagnostic probable d’au moins un syndrome clinique (surtout anxiété et dépression), 55 %, un diagnostic probable d’au moins un trouble de la personnalité; 30 %, des symptômes du trouble d’ÉSPT et 17,5 %, un diagnostic probable du trouble. Alors, la comorbidité est présente chez les joueurs pathologiques de l’échantillon. Il est essentiel de l’identifier pour mieux répondre aux besoins particuliers de l’individu et l’aider avec les symptômes qui aggravent le problème de jeu et augmentent le risque de récidive.

Portrait sociodémographique, anamnestique et psychopathologique des enfants placés en Centre jeunesse et à qui l'on prescrit des médicaments psychotropes.

Cette thèse a pour but de mieux comprendre le recours aux médicaments psychotropes chez les enfants hébergés en Centre jeunesse, une population qui compte parmi les plus médicalisées. Afin d’y parvenir, les caractéristiques sociodémographiques, anamnestiques et psychopathologiques des enfants placés qui reçoivent des psychopharmacoprescriptions ont été analysées. L’échantillon se compose de 101 enfants de 6 à 12 ans placés en foyer de groupe ou centre de réadaptation, dont 71 recevant des médicaments psychotropes. Les données ont été obtenues par le biais de questionnaires remplis par les éducateurs, par une entrevue semi-structurée réalisée auprès des enfants et une analyse du dossier. Sur le plan de la structure, cet ouvrage comprend une introduction, quatre articles et une conclusion. Le premier article comporte une recension des écrits sur l’usage de la psychopharmacothérapie chez les jeunes placés dans les services de la protection de la jeunesse. Il a été constaté que les taux de prescriptions peuvent varier entre 13% et 77%, selon le type de placement et les régions à l’étude. La symptomatologie des enfants placés qui reçoivent des médicaments psychotropes est caractérisée par des problèmes extériorisés et des troubles psychotiques. Les corrélats du recours à la prescription concernent à la fois la sévérité du tableau clinique, mais aussi le type et l’instabilité du placement, l’âge et le sexe de l’enfant ainsi que la formation des intervenants. Enfin, les écrits recensés font état de l’influence des neurosciences dans les milieux médicaux sur les décisions de prescrire. Le deuxième article présente la prévalence des psychopharmacoprescriptions chez les enfants de 6 à 12 ans placés hors d’un milieu familial. Les résultats indiquent que 70,3% des jeunes reçoivent au moins une prescription, le plus souvent signées par des médecins spécialistes. La plupart se composent de psychostimulants et d’antipsychotiques atypiques, prescrits pour des troubles de l’attention avec hyperactivité. Le troisième article cherche à préciser les caractéristiques sociodémographiques et anamnestiques des enfants placés qui prennent des médicaments psychotropes. Les résultats indiquent que les sujets médicamentés et non médicamentés ont vécu des stresseurs psychosociaux similaires. Par contre, les enfants placés qui reçoivent une psychopharmacothérapie ont été retirés de leur milieu familial à un plus jeune âge. Le quatrième article consiste à cibler leur portrait psychopathologique et à connaître leur niveau de fonctionnement global. Il s’intéresse également aux connaissances et aux perceptions des éducateurs sur la psychopharmacothérapie. Les résultats révèlent que les enfants médicamentés ont plus souvent un diagnostic de trouble mental inscrit à leur dossier. Selon les éducateurs, ils présentent davantage de problèmes extériorisés et intériorisés. À partir de données autorévélées, aucune distinction ne peut être établie entre les sujets, puisque les uns et les autres rapportent un niveau comparable de symptômes et de signes diagnostiques. Enfin, les symptômes de stress post-traumatique et l’opinion favorable des éducateurs sur la psychopharmacothérapie constituent des prédicteurs significatifs de la probabilité de recourir à un traitement médicamenteux. En conclusion, l’apport des résultats de cette recherche est analysé à la lumière des études antérieures. Les retombées cliniques sont discutées et des pistes de recherche futures sont suggérées. .

Genomic architecture of sickle cell disease clinical variation in children from West Africa : a case-control study design

Contexte : L’anémie falciforme ou drépanocytose est un problème de santé important, particulièrement pour les patients d’origine africaine. La variation phénotypique de l’anémie falciforme est problématique pour le suivi et le traitement des patients. L’architecture génomique responsable de cette variabilité est peu connue. Principe : Mieux saisir la contribution génétique de la variation clinique de cette maladie facilitera l’identification des patients à risque de développer des phénotypes sévères, ainsi que l’adaptation des soins. Objectifs : L’objectif général de cette thèse est de combler les lacunes relatives aux connaissances sur l’épidémiologie génomique de l’anémie falciforme à l’aide d’une cohorte issue au Bénin. Les objectifs spécifiques sont les suivants : 1) caractériser les profils d’expressions génomiques associés à la sévérité de l’anémie falciforme ; 2) identifier des biomarqueurs de la sévérité de l’anémie falciforme ; 3) identifier la régulation génétique des variations transcriptionelles ; 4) identifier des interactions statistiques entre le génotype et le niveau de sévérité associé à l’expression ; 5) identifier des cibles de médicaments pour améliorer l’état des patients atteints d’anémie falciforme. Méthode : Une étude cas-témoins de 250 patients et 61 frères et soeurs non-atteints a été menée au Centre de Prise en charge Médical Intégré du Nourrisson et de la Femme Enceinte atteints de Drépanocytose, au Bénin entre février et décembre 2010. Résultats : Notre analyse a montré que des profils d’expressions sont associés avec la sévérité de l’anémie falciforme. Ces profils sont enrichis de génes des voies biologiques qui contribuent à la progression de la maladie : l’activation plaquettaire, les lymphocytes B, le stress, l’inflammation et la prolifération cellulaire. Des biomarqueurs transcriptionnels ont permis de distinguer les patients ayant des niveaux de sévérité clinique différents. La régulation génétique de la variation de l’expression des gènes a été démontrée et des interactions ont été identifiées. Sur la base de ces résultats génétiques, des cibles de médicaments sont proposées. Conclusion: Ce travail de thèse permet de mieux comprendre l’impact de la génomique sur la sévérité de l’anémie falciforme et ouvre des perspectives de développement de traitements ciblés pour améliorer les soins offerts aux patients.

The Role of Obsessive Beliefs and Inferential Confusion in Predicting Treatment Outcomes for Different Subtypes of Obsessive-Compulsive Disorder

Essai doctoral d’intégration Présenté en vue de l’obtention du doctorat (D.Psy.)

Las adicciones a la luz del psicoanálisis, una revisión de literatura

El presente trabajo de grado es una revisión de la literatura que permite hacer un recorrido desde el psicoanálisis acerca de la compleja problemática de las adicciones. Para ello, se revisaron las bases de datos PepWeb, Ebsco, y Jstor, revisando las posiciones del psicoanálisis freudiano, lacaniano y otras corrientes psicoanalíticas respondiendo a las siguientes preguntas de investigación: (a) ¿Cómo se comprenden las adicciones desde un marco de referencia psicoanalítico? (b) ¿Cómo –desde la teoría freudiana y la teoría lacaniana - se aborda la comprensión de la adicción? (c) ¿Qué dice el psicoanálisis contemporáneo sobre ésta problemática? Se abordan temas como la concepción de una adicción desde la perspectiva de Freud y Lacan hasta psicoanalistas contemporáneos, el rol que juega el goce en la adicción y, finalmente, el complejo debate incipiente sobre la legalidad del tóxico. Se encontró que es un campo de constante publicación y es necesario que los clínicos y los psicoanalistas aborden este campo de estudio clínico permanentemente y sigan produciendo investigaciones sobre el fenómeno.

Diagnostic concordance of DSM-IV and DSM-5 Posttraumatic Stress Disorder (PTSD) in a clinical sample

Resumen tomado de la publicaci??n

Learning and memory in holocaust survivors with posttraumatic stress disorder

Background: Impairments in explicit memory have been observed in Holocaust survivors with posttraumatic stress disorder. Methods: To evaluate which memory components are preferentially affected, the California Verbal Learning Test was administered to Holocaust survivors with (n = 36) and without (n = 26) posttraumatic stress disorder, and subjects not exposed to the Holocaust (n = 40). Results: Posttraumatic stress disorder subjects showed impairments in learning and short-term and delayed retention compared to nonexposed subjects; survivors without posttraumatic stress disorder did not. Impairments in learning, but not retention, were retained after controlling fir intelligence quotient. Older age was associated with poorer learning and memory performance in the posttraumatic stress disorder group only. Conclusions: The most robust impairment observed in posttraumatic stress disorder was in verbal learning, which may be a risk factor for or consequence of chronic posttraumatic stress disorder. The negative association between performance and age may reflect accelerated cognitive decline in posttraumatic stress disorder.

Attention disengagement in children with developmental coordination disorder

Purpose. Previous research has shown that children with Developmental Coordination Disorder (DCD) have poorly developed strategies for allocating attention. This study examines the allocation of attention and integration of visuo-spatial and motor systems in children with DCD in a motor (look+hit condition) and a motor-free (look condition) task. Method. Three groups of control children were used to compare the performance of a group of children with DCD. Children were seated in front of a central fixation point and six peripheral targets, and were asked to look at or hit targets when illuminated. Saccade/hand movement latencies were measured on gap trials (gap between fixation offset and target onset) and overlap trials (fixation offset and target onset overlapped). Results. DCD children were not slower than controls to disengage attention during the look condition. However, during the look+hit condition the DCD children showed a prolonged disengagement period, which was also seen in younger control children. Conclusions. The results suggest that DCD children may have deficits in the allocation of attention for action, in both the speed of onset of a movement and the accuracy of the movement. It is concluded that attention disengagement may contribute to problems of visuo-motor integration in DCD.