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

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.

Keyphrases: adolescence, IRMf, extinction, harsh parenting, adversity, anxiety, youth, fear conditioning, fMRI, amygdala, sex, gender