Pratiques parentales coercitives, anxiété et traitement de la peur chez les jeunes en bonne santé: corrélats neuronaux, biologiques, physiologiques et comportementaux

L’adversité tôt dans la vie est associée au développement de symptômes anxieux pouvant perdurer jusqu’à l’âge adulte (Casey et el, 2010, Pine 2003). Des études chez l’adulte suggèrent que ces liens pourraient être associés à des altérations du « circuit de la peur » qui inclut l’amygdale, l’hippocampe antérieur, l’insula et le cortex préfrontal (Marek, 2013, Etkin & Wager, 2007). Ceci a cependant peu été étudié chez les jeunes. L’objectif principal de cette thèse était de définir les corrélats comportementaux, physiologiques, biologiques et neuronaux du traitement de la peur chez les jeunes en bonne santé, en lien ou non avec un historique d’adversité -- sous la forme de pratiques parentales coercitives -- et d’anxiété. D’abord, puisque nous nous intéressions aux pratiques parentales coercitives chroniques, nous avons examiné leur évolution et facteurs de risque, en nous concentrant sur la période de 17 à 72 mois. Un total de 2045 dyades mère-enfant ont été incluses dans une analyse de courbe de croissance latente. Nous avons démontré que la coercition maternelle suit une évolution non linéaire durant cette période et atteint un sommet à 42 mois. Les facteurs de risque relatifs à l’enfant et à la mère, mesurés à 17 mois, permettent de prédire les niveaux de coercition à 42 mois. Finalement, les prédicteurs relatifs à l’enfant et l’efficacité maternelle prédisent l’évolution des pratiques parentales coercitives entre 17 et 72 mois. Ensuite, afin de définir une méthodologie solide pour étudier le traitement de la peur chez des jeunes, nous avons adapté une tâche développée par Lau et ses collaborateurs (2008), employant des visages féminins comme stimuli. Le sexe des participants et des visages employés comme stimuli pouvant potentiellement moduler le traitement de la peur (Kret & de Gelder, 2012; McClure, 2000), nous avons étudié leurs influences respectives sur les réponses électrodermales et subjectives de peur durant le conditionnement et l’extinction de la peur chez 117 jeunes. Nous avons démontré que les stimuli féminins suscitent des réponses davantage comparables entre les garçons et les filles que les stimuli masculins. De plus, nous avons observé un effet du « même sexe », caractérisé par un conditionnement différentiel uniquement face aux stimuli du même sexe que le participant. Finalement, nous avons exploré les différences individuelles et conjointes associées aux différents niveaux de pratiques parentales coercitives et d’anxiété en termes de réponses de peur et d’activité cérébrale, durant le conditionnement et l’extinction de la peur chez 84 jeunes. Nous avons démontré que la coercition est spécifiquement associée au fonctionnement du lobe temporal médian et aux interactions entre l’amygdale et l’insula, durant le conditionnement. Durant l’extinction, les niveaux d’anxiété étaient associés à des différences spécifiques d’activation du gyrus cingulaire antérieur (GCA) dorsal. Enfin, les pratiques parentales coercitives et l’anxiété interagissent et viennent moduler la connectivité fonctionnelle amygdale - GCA rostral, l’activation d’une sous-région du GCA dorsal et les réponses subjectives de peur. Ces résultats ajoutent une pièce au casse-tête des neurosciences développementales et fournissent des pistes intéressantes pour le développement d’interventions futures.Early-life adversity is associated with increased risks of developing anxiety symptoms that can persist throughout the lifespan (Casey et al, 2010 Pine 2003). Adult literature suggests that these links could be mediated by alterations of the "fear circuitry " a neural system that includes the amygdala, anterior hippocampus, insula and prefrontal cortex (Marek, 2013, Etkin & Wager, 2007). This, however, has scarcely been studied in youth. The main objective of the present thesis was to investigate the behavioral, physiological, biological and neural correlates of fear processing in physically and psychiatrically healthy youth, associated or not with a history of early-life adversity -- under the form of maternal harsh parenting -- and anxiety. First, since we were interested in chronic harsh parenting levels, we examined the longitudinal evolution and risk factors of maternal harsh parenting practices between child age 17 months and 6 years in 2045 mother-child dyads. During this period, harsh parenting was found to follow a non-linear trajectory, with a peak at 42 months. Risk factors related to the child (i.e. sex and internalized and externalized behaviors) and the mother (i.e. history of depression and perceived parental self-efficacy) measured at 17 months predicted harsh parenting levels at 42 months. As well, child risk factors and maternal self-efficacy predicted harsh parenting evolution between 17 and 72 months. Second, in order to establish a robust methodology to investigate fear processing in a pediatric population, we adapted a paradigm developed by Lau and collaborators (2008) employing female faces as conditioned and unconditional stimuli. Since sex of participants and sex of faces used as emotional stimuli may modulate fear processing (Kret & De Gelder; McClure, 2000), we examined their respective influences on objective (skin conductance responses or SCRs) and subjective (fear ratings) fear responses during discrimination fear conditioning and extinction tasks in 117 adolescents. This study demonstrated that female stimuli elicit more constant and comparable fear responses in boys and girls relative to male stimuli. In addition, an “own sex effect” was observed for SCRs, illustrated by discrimination conditioning taking place only in boys viewing male faces and in girls viewing female faces. Finally, we explored the individual and joint differences associated with maternal harsh parenting practices and anxiety levels in terms of objective, subjective, and brain activity responses during the conditioning and extinction of fear in 84 youths. This study demonstrated that harsh parenting practices are specifically associated with differences in medial temporal lobe function and in amygdala-insula functional connectivity during conditioning. During extinction, anxiety levels were associated with specific activation differences in the dorsal anterior cingulate cortex (ACC). Finally, harsh parenting and anxiety were found to interact and modulated differences in activations in a smaller dorsal ACC cluster, in amygdala-rostral ACC functional connectivity, and in subjective fear responses. These results add a piece to the puzzle of developmental neurosciences and provide guidelines for the development of future better-targeted interventions

Localisation of unilateral nasal stimuli across sensory systems

Odor stimuli presented to one nostril can only be localised if they additionally activate the trigeminal nerve’s chemosensitive fibers. In this study we aimed to investigate characteristics in the localisation of unilateral trigeminal, olfactory and somatosensory nasal stimuli. We compared the ability of healthy young subjects to localise monorhinally presented (a) pure olfactory stimuli (phenyl ethyl alcohol), (b) mixed olfactory trigeminal stimuli (eucalyptol), and (c) somatosensory stimuli (air puffs). As expected, subjects could localise the air puffs and eucalyptol, but could not phenyl ethyl alcohol. Interestingly, we observed a significant correlation between localisation performance for eucalyptol and phenyl ethyl alcohol but not between the ability to localise somatosensory and trigeminal or olfactory stimuli. These observations show that on a behavioural level, the trigeminal chemosensory system is more intimately connected to the olfactory system than to the somatosensory system despite the fact that anatomically its information is conveyed via same nerve as the latter. Furthermore, they show that the trigeminal chemosensory system should therefore be considered a self-confined contributor to chemosensory perception

The conditioning and extinction of fear in youths: What's sex got to do with it?

a b s t r a c t Adult work shows differences in emotional processing influenced by sexes of both the viewer and expresser of facial expressions. We investigated this in 120 healthy youths (57 boys; 10-17 years old) randomly assigned to fear conditioning and extinction tasks using either neutral male or female faces as the conditioned threat and safety cues, and a fearful face paired with a shrieking scream as the unconditioned stimulus. Fear ratings and skin conductance responses (SCRs) were assessed. Male faces triggered increased fear ratings in all participants during conditioning and extinction. Greater differential SCRs were observed in boys viewing male faces and in girls viewing female faces during conditioning. During extinction, differential SCR findings remained significant in boys viewing male faces. Our findings demonstrate how sex of participant and sex of target interact to shape fear responses in youths, and how the type of measure may lead to distinct profiles of fear responses

The Impact of Comorbidity on Cognitive-Behavioral Therapy Response in Youth with Anxiety and Autism Spectrum Disorder

The impact of externalizing comorbidity on treatment outcome was examined in 104 youth ages 7-16 (M = 11.09 years) with autism spectrum disorder and primary anxiety/obsessive compulsive disorder who completed modular cognitive behavioral therapy (CBT) for anxiety/OCD. Three comorbidity profiles were utilized for group comparisons: participants with oppositional defiant or conduct disorder with attention-deficit hyperactivity disorder (ODD; CD; ADHD; group EXT, n = 25); those without ODD/CD and only ADHD (group ADHD, n = 46); and those without externalizing comorbidity (NO-EXT, n = 33). Post-treatment outcomes were measured continuously (Pediatric Anxiety Rating Scale, Clinical Global Impression-Severity) and categorically (treatment response, remission). The ADHD group was four times more likely of being a treatment responder compared to NO-EXT (OR 4.05). Comorbidity group did not impact remission. After controlling for pre-treatment scores, there was a significantly greater reduction of the CGI-S for ADHD versus NO-EXT and EXT versus NO-EXT, but results did not significantly differ for the PARS. Results suggest that a modular CBT approach yields positive impact for treatment outcomes in youth with comorbid externalizing problems, particularly among those with comorbid ADHD