Le neurofeedback (NF) suscite actuellement un vif intérêt dans la prise en charge du trouble déficitaire de l’attention avec hyperactivité (TDAH) chez l’enfant. Proposée comme méthode alternative à la médication par de nombreux cliniciens, notamment aux États-Unis, le NF est une intervention non-invasive de type électrophysiologique qui repose sur l’apprentissage par conditionnement opérant de l’autorégulation d’ondes cérébrales déviantes. Les études empiriques qui étayent cette pratique font toutefois l’objet de virulentes critiques de la part de spécialistes dans le domaine du TDAH en raison de résultats systématiquement positifs mais non spécifiques, auxquels s’ajoutent de nombreuses lacunes méthodologiques. Les travaux de cette thèse visent à appliquer une méthodologie stricte de type essai clinique contrôlé avec assignation aléatoire afin d’isoler les effets particuliers du NF, en appliquant un protocole d’entraînement propre au déficit primaire sous-tendant le TDAH, soit l’inhibition motrice, dans le but d’évaluer la spécificité de cette intervention. Dans un premier temps, les connaissances relatives à la nosologie du TDAH, à ses principaux traitements, au NF et aux capacités d’inhibition chez l’enfant ayant un TDAH sont présentées (Chapitre 1). Ensuite, les études réalisées dans le cadre de cette thèse sont exposées. Dans l’étude initiale, la spécificité du NF est évaluée sur les capacités d’inhibition grâce à des mesures subjectives, soit des questionnaires de comportements complétés par les parents, ainsi que des mesures objectives, à savoir des tâches neuropsychologiques (Chapitre 2). Afin de préciser davantage les conséquences d’un entraînement à l’autorégulation d’ondes cérébrales, l’étude subséquente s’est intéressée à l’impact neurophysiologiques de l’amélioration des capacités d’inhibition, par le biais d’une étude en potentiels évoqués employant une tâche de performance continue de type Stop-signal (Chapitre 3). Les principaux résultats reflètent un recrutement sous optimal, avec une puissance statistique insuffisante pour réaliser des statistiques quantitatives de groupe. Néanmoins, l’appréciation des données selon une approche d’étude de cas multiples permet de mettre en évidence la présence d’une réponse placebo sur les capacités d’inhibition suite à un entraînement en NF. Finalement, les implications de la taille de l’échantillon, ainsi que les limites et les critiques de ces études sont discutées au Chapitre 4. / In recent years, there has been a lively interest in the use of neurofeedback (NF) as an alternative treatment to pharmacotherapy in pediatric Attention-deficit hyperactivity disorder (ADHD). NF is defined as an operant conditioning procedure whereby an individual learns to self-regulate electrical brain activity. Yet, empirical studies supporting its practice are harshly criticized in the field of ADHD research due to systematic unspecific positive results associated to numerous methodological flaws. Studies presented in this dissertation aim at applying a randomized placebo-controlled clinical trial to the investigation of NF specific effects. In order to further establish treatment specificity, we trained the participants using a NF protocol characteristic to motor-inhibition functioning since it has repeatedly been described as the core deficit in ADHD. The fist part of this thesis comprises a brief review of knowledge concerning ADHD, principal treatments offered for this disorder, NF research in pediatric ADHD and inhibition abilities in these children (Chapter 1). Following are the two studies conducted as part of this dissertation. In the initial study, effects of NF training are investigated on inhibition capacities by means of behavior rating scales and neuropsychological tests (Chapter 2). With the aim of further defining the consequence of training to self-regulate ones brain activity, the subsequent study looks at the neurophysiologic impact of improving inhibition capacities with an event-related potential study using a Stop-signal continuous performance task (Chapter 3). The principal results reveal a non optimal recruitment, with insufficient statistical power, thus precluding quantitative group statistics. Nevertheless, appreciating the data from a multiple case study perspective enables to suggest that a placebo response could be at play following NF training, such as measured by improvements on inhibition capacities. Finally, the implications of such a small sample size, limits and critics of these studies are discussed in Chapter 4.

Le neurofeedback (NF) suscite actuellement un vif intérêt dans la prise en charge du trouble déficitaire de l’attention avec hyperactivité (TDAH) chez l’enfant. Proposée comme méthode alternative à la médication par de nombreux cliniciens, notamment aux États-Unis, le NF est une intervention non-invasive de type électrophysiologique qui repose sur l’apprentissage par conditionnement opérant de l’autorégulation d’ondes cérébrales déviantes. Les études empiriques qui étayent cette pratique font toutefois l’objet de virulentes critiques de la part de spécialistes dans le domaine du TDAH en raison de résultats systématiquement positifs mais non spécifiques, auxquels s’ajoutent de nombreuses lacunes méthodologiques. Les travaux de cette thèse visent à appliquer une méthodologie stricte de type essai clinique contrôlé avec assignation aléatoire afin d’isoler les effets particuliers du NF, en appliquant un protocole d’entraînement propre au déficit primaire sous-tendant le TDAH, soit l’inhibition motrice, dans le but d’évaluer la spécificité de cette intervention. Dans un premier temps, les connaissances relatives à la nosologie du TDAH, à ses principaux traitements, au NF et aux capacités d’inhibition chez l’enfant ayant un TDAH sont présentées (Chapitre 1). Ensuite, les études réalisées dans le cadre de cette thèse sont exposées. Dans l’étude initiale, la spécificité du NF est évaluée sur les capacités d’inhibition grâce à des mesures subjectives, soit des questionnaires de comportements complétés par les parents, ainsi que des mesures objectives, à savoir des tâches neuropsychologiques (Chapitre 2). Afin de préciser davantage les conséquences d’un entraînement à l’autorégulation d’ondes cérébrales, l’étude subséquente s’est intéressée à l’impact neurophysiologiques de l’amélioration des capacités d’inhibition, par le biais d’une étude en potentiels évoqués employant une tâche de performance continue de type Stop-signal (Chapitre 3). Les principaux résultats reflètent un recrutement sous optimal, avec une puissance statistique insuffisante pour réaliser des statistiques quantitatives de groupe. Néanmoins, l’appréciation des données selon une approche d’étude de cas multiples permet de mettre en évidence la présence d’une réponse placebo sur les capacités d’inhibition suite à un entraînement en NF. Finalement, les implications de la taille de l’échantillon, ainsi que les limites et les critiques de ces études sont discutées au Chapitre 4. / In recent years, there has been a lively interest in the use of neurofeedback (NF) as an alternative treatment to pharmacotherapy in pediatric Attention-deficit hyperactivity disorder (ADHD). NF is defined as an operant conditioning procedure whereby an individual learns to self-regulate electrical brain activity. Yet, empirical studies supporting its practice are harshly criticized in the field of ADHD research due to systematic unspecific positive results associated to numerous methodological flaws. Studies presented in this dissertation aim at applying a randomized placebo-controlled clinical trial to the investigation of NF specific effects. In order to further establish treatment specificity, we trained the participants using a NF protocol characteristic to motor-inhibition functioning since it has repeatedly been described as the core deficit in ADHD. The fist part of this thesis comprises a brief review of knowledge concerning ADHD, principal treatments offered for this disorder, NF research in pediatric ADHD and inhibition abilities in these children (Chapter 1). Following are the two studies conducted as part of this dissertation. In the initial study, effects of NF training are investigated on inhibition capacities by means of behavior rating scales and neuropsychological tests (Chapter 2). With the aim of further defining the consequence of training to self-regulate ones brain activity, the subsequent study looks at the neurophysiologic impact of improving inhibition capacities with an event-related potential study using a Stop-signal continuous performance task (Chapter 3). The principal results reveal a non optimal recruitment, with insufficient statistical power, thus precluding quantitative group statistics. Nevertheless, appreciating the data from a multiple case study perspective enables to suggest that a placebo response could be at play following NF training, such as measured by improvements on inhibition capacities. Finally, the implications of such a small sample size, limits and critics of these studies are discussed in Chapter 4.

Os estudos publicados nos últimos anos sobre a utilização da estimulação magnética transcraniana de repetição (EMTr) têm sugerido significativas ações antidepressivas. Neste trabalho foi realizado um estudo comparativo da EMTr com a eletroconvulsoterapia (ECT) que é um método consagrado para o tratamento de transtornos depressivos. Foi feita, em primeiro lugar, uma extensa revisão a respeito destes dois métodos de tratamento não medicamentoso, expondo a sua história, a sua eficácia, as principais indicações, contra-indicações e efeitos colaterais, além dos possíveis mecanismos de ação, que ainda não estão completamente esclarecidos. A seguir foi realizado um ensaio clínico controlado, randomizado, simples-cego, comparando a eficácia de ambos para o tratamento da Depressão Maior unipolar refratária, sem sintomas psicóticos, com indicação de ECT. Também foi realizada uma avaliação dos efeitos cognitivos, especialmente da memória. Trinta e cinco pacientes foram incluídos. A eletroconvulsoterapia foi realizada com indução anestésica geral e relaxamento muscular. Foram feitas aplicações na posição unilateral direita com carga 4,5 vezes o limiar convulsígeno. A EMTr foi aplicada no córtex pré-frontal dorso-lateral esquerdo com intensidade de 100% do limiar motor. Os pacientes receberam 20 sessões (cinco dias por semana por quatro semanas), com 25 séries de estimulação por dia (com freqüência de 10 Hz por 10 segundos, com intervalos de 20 segundos). As escalas de avaliação foram aplicadas nos tempos basal, após duas semanas de tratamento e após quatro semanas de tratamento. Ambos os tratamentos tiveram eficácia equivalente, com uma taxa de redução média dos escores na escala de Hamilton para depressão de 42 %, uma resposta clínica de 46 % e uma taxa de remissão de 14%. A EMTr apresentou um perfil mais benigno de efeitos colaterais (cefaléia em 1 %). A ECT resultou em cefaléia (em 20 %) e náuseas (em 10%).Não houve diferença nos efeitos cognitivos entre os dois tratamentos, tendo ambos se mostrado bastante benignos. Este estudo é uma contribuição para a crescente literatura a respeito do assunto e sugere um efeito antidepressivo da EMTr, comparável ao da ECT em pacientes com depressão maior unipolar sem sintomas psicóticos / Studies published over the past few years suggest that repetitive transcranial magnetic stimulation (rTMS) may have significant antidepressant actions. This work performs a comparison between rTMS and electroconvulsive therapy (ECT), an established method to treat depression disorders. First there was an extensive review on the knowledge of both non pharmacological treatments including their history, efficacy, main indications, contraindications and side effects, in addition to the possible mechanisms of action, not yet fully understood. After that, a controlled randomized, single-blind clinical trial was conducted, comparing the efficacy to treat unipolar resistant nonpsychotic major depression that were referred to receive ECT. An evaluation of cognitive effects was also performed, specially memory effects. Thirty five patients were included. Electroconvulsive therapy was performed with general anesthesia and muscular relaxation. Right unilateral electrodes positioning was used, with a charge 4.5 times the convulsive threshold. rTMS was performed over the left dorsolateral prefrontal cortex at 100% motor threshold. Patients were treated with 20 sessions (five times per week for four weeks) with 25 trains a day (frequency of 10 Hz, duration of 10 seconds with 20 seconds intertrain interval). Patients were evaluated at baseline, after two weeks and after four weeks of either treatment. Both groups were equivalent in efficacy, showing a means of reduction on Hamilton depression rating scale of 42%, an overall clinical response of 46% and a remission rate of 14%. rTMS showed a more benign profile regarding side effects (headache on 1%). ECT induced headache (20%) and nausea (10%). No cognitive effects were observed on either treatments. This study adds to the growing literature supporting an antidepressant effect for rTMS, similar to ECT on patients with unipolar nonpsychotic major depression

Os estudos publicados nos últimos anos sobre a utilização da estimulação magnética transcraniana de repetição (EMTr) têm sugerido significativas ações antidepressivas. Neste trabalho foi realizado um estudo comparativo da EMTr com a eletroconvulsoterapia (ECT) que é um método consagrado para o tratamento de transtornos depressivos. Foi feita, em primeiro lugar, uma extensa revisão a respeito destes dois métodos de tratamento não medicamentoso, expondo a sua história, a sua eficácia, as principais indicações, contra-indicações e efeitos colaterais, além dos possíveis mecanismos de ação, que ainda não estão completamente esclarecidos. A seguir foi realizado um ensaio clínico controlado, randomizado, simples-cego, comparando a eficácia de ambos para o tratamento da Depressão Maior unipolar refratária, sem sintomas psicóticos, com indicação de ECT. Também foi realizada uma avaliação dos efeitos cognitivos, especialmente da memória. Trinta e cinco pacientes foram incluídos. A eletroconvulsoterapia foi realizada com indução anestésica geral e relaxamento muscular. Foram feitas aplicações na posição unilateral direita com carga 4,5 vezes o limiar convulsígeno. A EMTr foi aplicada no córtex pré-frontal dorso-lateral esquerdo com intensidade de 100% do limiar motor. Os pacientes receberam 20 sessões (cinco dias por semana por quatro semanas), com 25 séries de estimulação por dia (com freqüência de 10 Hz por 10 segundos, com intervalos de 20 segundos). As escalas de avaliação foram aplicadas nos tempos basal, após duas semanas de tratamento e após quatro semanas de tratamento. Ambos os tratamentos tiveram eficácia equivalente, com uma taxa de redução média dos escores na escala de Hamilton para depressão de 42 %, uma resposta clínica de 46 % e uma taxa de remissão de 14%. A EMTr apresentou um perfil mais benigno de efeitos colaterais (cefaléia em 1 %). A ECT resultou em cefaléia (em 20 %) e náuseas (em 10%).Não houve diferença nos efeitos cognitivos entre os dois tratamentos, tendo ambos se mostrado bastante benignos. Este estudo é uma contribuição para a crescente literatura a respeito do assunto e sugere um efeito antidepressivo da EMTr, comparável ao da ECT em pacientes com depressão maior unipolar sem sintomas psicóticos / Studies published over the past few years suggest that repetitive transcranial magnetic stimulation (rTMS) may have significant antidepressant actions. This work performs a comparison between rTMS and electroconvulsive therapy (ECT), an established method to treat depression disorders. First there was an extensive review on the knowledge of both non pharmacological treatments including their history, efficacy, main indications, contraindications and side effects, in addition to the possible mechanisms of action, not yet fully understood. After that, a controlled randomized, single-blind clinical trial was conducted, comparing the efficacy to treat unipolar resistant nonpsychotic major depression that were referred to receive ECT. An evaluation of cognitive effects was also performed, specially memory effects. Thirty five patients were included. Electroconvulsive therapy was performed with general anesthesia and muscular relaxation. Right unilateral electrodes positioning was used, with a charge 4.5 times the convulsive threshold. rTMS was performed over the left dorsolateral prefrontal cortex at 100% motor threshold. Patients were treated with 20 sessions (five times per week for four weeks) with 25 trains a day (frequency of 10 Hz, duration of 10 seconds with 20 seconds intertrain interval). Patients were evaluated at baseline, after two weeks and after four weeks of either treatment. Both groups were equivalent in efficacy, showing a means of reduction on Hamilton depression rating scale of 42%, an overall clinical response of 46% and a remission rate of 14%. rTMS showed a more benign profile regarding side effects (headache on 1%). ECT induced headache (20%) and nausea (10%). No cognitive effects were observed on either treatments. This study adds to the growing literature supporting an antidepressant effect for rTMS, similar to ECT on patients with unipolar nonpsychotic major depression