Low- vs High-Frequency Repetitive Transcranial Magnetic Stimulation as an Add-On Treatment for Refractory Depression

Objectives: Repetitive transcranial magnetic stimulation (rTMS) seems to be effective as an antidepressant, however, some confusion remains about the best parameters to apply and the efficacy of its association with pharmacological antidepressant treatments. Method: In a single blind randomized study 14 patients with unipolar resistant depression to one antidepressant treatment were enrolled to receive, in combination with venlafaxine (150 mg), either 20 sessions of 10 Hz rTMS (2000 pulses per session) applied over the left dorsolateral prefrontal cortex (DLPFC) or 20 sessions of 1 Hz rTMS (120 stimulations per sessions) applied over the right DLPFC. Results: A similar antidepressant effect was observed in both groups with a comparable antidepressant delay of action (2 weeks) and a comparable number of responders (MADRS < 15) after 4 weeks of daily rTMS sessions (66 vs 50%). Conclusion: Low- and high- frequency rTMS seems to be effective as an add-on treatment to venlafaxine as monotherapy in pharmacological refractory major depression (stage 1). Due to its short duration (one session of 1 Hz rTMS lasts 4 min vs 16 for 10 Hz rTMS) and its safety, low frequency rTMS may be a useful alternative treatment for patients with refractory depression

Integrity of the arcuate fasciculus in patients with schizophrenia with auditory verbal hallucinations: A DTI-tractography study

AbstractAuditory verbal hallucinations (AVH) of schizophrenia are associated with a disrupted connectivity between frontal and temporoparietal language areas. We hypothesized that this dysconnectivity is underpinned by white matter abnormalities in the left arcuate fasciculus, the main fiber bundle connecting speech production and perception areas. We therefore investigated the relationship between AVH severity and the integrity of the arcuate fasciculus measured by diffusion tensor imaging (DTI) tractography in patients with schizophrenia.Thirty-eight patients with treatment-resistant schizophrenia were included: 26 presented with daily severe treatment-resistant AVH, 12 reported prominent negative symptoms and no AVH. Fractional anisotropy (FA) was measured along the length of the left and right anterior arcuate fasciculi and severity of AVH was assessed using P3 PANSS item.FA values were significantly higher in the left arcuate fasciculus in patients with AVH than in no AVH patients (F(1,35)=3.86; p=0.05). No difference was observed in the right arcuate fasciculus. There was a significant positive correlation between FA value in the left arcuate fasciculus and the severity of AVH (r=0.36; p=0.02). No correlation was observed between FA values and PANSS total score suggesting a specific relationship between AVH severity and the left arcuate fasciculus integrity.These results support the hypothesis of a relationship between left frontotemporal connectivity and AVH in patients with schizophrenia and suggest that whilst a disruption of frontotemporal connectivity might be present to ensure the emergence of AVH, more severe anatomical alterations may prevent the occurrence of AVH in patients with schizophrenia

Transcranial Direct Current Stimulation for Obsessive-Compulsive Disorder: A Systematic Review

Despite the advances in psychopharmacology and established psychotherapeutic interventions, more than 40% of patients with obsessive-compulsive disorder (OCD) do not respond to conventional treatment approaches. Transcranial direct current stimulation (tDCS) has been recently proposed as a therapeutic tool to alleviate treatment-resistant symptoms in patients with OCD. The aim of this review was to provide a comprehensive overview of the current state of the art and future clinical applications of tDCS in patients with OCD. A literature search conducted on the PubMed database following PRISMA guidelines and completed by a manual search yielded 12 results: eight case reports, three open-label studies (with 5, 8, and 42 participants), and one randomized trial with two active conditions (12 patients). There was no sham-controlled study. A total of 77 patients received active tDCS with a large diversity of electrode montages mainly targeting the dorsolateral prefrontal cortex, the orbitofrontal cortex or the (pre-) supplementary motor area. Despite methodological limitations and the heterogeneity of stimulation parameters, tDCS appears to be a promising tool to decrease obsessive-compulsive symptoms as well as comorbid depression and anxiety in patients with treatment-resistant OCD. Further sham-controlled studies are needed to confirm these preliminary results

Clinical, cognitive and neural effects of transcranial direct current stimulation in patients with schizophrenia and auditory hallucinations

Les hallucinations auditives sont un symptôme fréquent et invalidant de la schizophrénie. Bien qu'habituellement jugulés par des traitements antipsychotiques, ces symptômes sont résistants dans 25 % des cas et leur physiopathologie reste méconnue. Dans ce travail de thèse, nous proposons d'utiliser la stimulation transcrânienne en courant continu (tDCS) dans une série d'études afin de traiter et de caractériser les hallucinations auditives résistantes de la schizophrénie. Dans une première série d'études cliniques, nous avons rapporté que la tDCS fronto-temporale diminuait les hallucinations auditives de la schizophrénie. Dans une autre étude, nous avons montré que la diminution des hallucinations auditives était corrélée à l'amélioration des processus cognitifs de source- monitoring chez les patients. Dans une étude chez des sujets sains, nous avons montré que ces processus cognitifs étaient liés à l'activité de la jonction temporo-pariétale gauche. Enfin, dans une étude d'imagerie, nous avons montré que la tDCS fronto-temporale modulait la connectivité fonctionnelle de la jonction temporo-pariétale gauche avec un large réseau cérébral impliqué dans les hallucinations et le traitement du langage. L'étude des effets cliniques, cognitifs et neurophysiologiques de la tDCS nous a permis de mieux comprendre la physiopathologie des hallucinations auditives et notamment le rôle central de la jonction temporo-pariétale gauche. Ces travaux seront mis en relation et confrontés à la littérature existante, afin de proposer des perspectives de prise en charge des hallucinations auditivesAuditory hallucinations are prominent and disabling features of schizophrenia. For 25%-30% of patients with schizophrenia, such hallucinations are refractory to drug treatment and their physiopathology remains unknown. This thesis aims at using transcranial direct current stimulation (tDCS) in several studies to alleviate and characterize refractory auditory hallucinations in schizophrenia. First, we conducted a clinical study in patients with schizophrenia and we reported that fronto-temporal tDCS reduced auditory hallucinations. ln another study, we reported that the reduced severity of auditory hallucinations was correlated with improved source monitoring performances. ln a study in healthy volunteers, we reported that source-monitoring processes were associated with activity of the left temporo-parietal junction. Finally, using functional magnetic resonance imaging, we observed that tDCS modulates the functional connectivity of the left temporo-parietal junction with a distributed network involved in auditory hallucinations and language processing. The study of clinical, cognitive and neural effects of tDCS allows a better understanding of brain mechanisms involved in auditory hallucinations and of the central role of the left temporo-parietal junction. These works were discussed together in light of available literature to pave the way for valuable alternative approaches to alleviate auditoryhallucinations in schizophreni