Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare life-threatening disease cau... more Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare life-threatening disease caused by enzyme inhibition or clearance of ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type 1 repeats 13), which leads to platelet aggregation in the microvasculature. 1 The role of ADAMTS13, also known as von Willebrand factor cleaving protease, is to break down ultra-large von Willebrand factor multimers. During an acute iTTP episode,
Despite the known benefits of data‐driven approaches, the lack of approaches for identifying func... more Despite the known benefits of data‐driven approaches, the lack of approaches for identifying functional neuroimaging patterns that capture both individual variations and inter‐subject correspondence limits the clinical utility of rsfMRI and its application to single‐subject analyses. Here, using rsfMRI data from over 100k individuals across private and public datasets, we identify replicable multi‐spatial‐scale canonical intrinsic connectivity network (ICN) templates via the use of multi‐model‐order independent component analysis (ICA). We also study the feasibility of estimating subject‐specific ICNs via spatially constrained ICA. The results show that the subject‐level ICN estimations vary as a function of the ICN itself, the data length, and the spatial resolution. In general, large‐scale ICNs require less data to achieve specific levels of (within‐ and between‐subject) spatial similarity with their templates. Importantly, increasing data length can reduce an ICN's subject‐le...
Background: Recent advances in data-driven computational approaches have been helpful in devising... more Background: Recent advances in data-driven computational approaches have been helpful in devising tools to objectively diagnose psychiatric disorders. However, current machine learning studies limited to small homogeneous samples, different methodologies, and different imaging collection protocols, limit the ability to directly X. Zhu et al.
Single-voxel proton magnetic resonance spectroscopy (SV 1H-MRS) is an in vivo noninvasive imaging... more Single-voxel proton magnetic resonance spectroscopy (SV 1H-MRS) is an in vivo noninvasive imaging technique used to detect neurotransmitters and metabolites. It enables repeated measurements in living participants to build explanatory neurochemical models of psychiatric symptoms and testing of therapeutic approaches.
Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare life-threatening disease cau... more Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare life-threatening disease caused by enzyme inhibition or clearance of ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type 1 repeats 13), which leads to platelet aggregation in the microvasculature. 1 The role of ADAMTS13, also known as von Willebrand factor cleaving protease, is to break down ultra-large von Willebrand factor multimers. During an acute iTTP episode,
Patients with CM-TMA, despite remission, have significant white matter changes on MRI and lower s... more Patients with CM-TMA, despite remission, have significant white matter changes on MRI and lower scores on neurocognitive testing.
ObjectiveOne factor potentially contributing to the heterogeneity of previous results on structur... more ObjectiveOne factor potentially contributing to the heterogeneity of previous results on structural grey matter alterations in adult participants suffering from post‐traumatic stress disorder (PTSD) is the varying levels of dissociative symptomatology. The aim of this study was therefore to test whether the recently defined dissociative subtype of PTSD characterized by symptoms of depersonalization and derealization is characterized by specific differences in volumetric brain morphology.MethodWhole‐brain MRI data were acquired for 59 patients with PTSD. Voxel‐based morphometry was carried out to test for group differences between patients classified as belonging (n = 15) vs. not belonging (n = 44) to the dissociative subtype of PTSD. The correlation between dissociation (depersonalization/derealization) severity and grey matter volume was computed.ResultsPatients with PTSD classified as belonging to the dissociative subtype exhibited greater grey matter volume in the right precentral and fusiform gyri as well as less volume in the right inferior temporal gyrus. Greater dissociation severity was associated with greater volume in the right middle frontal gyrus.ConclusionThe results of this first whole‐brain investigation of specific grey matter volume in dissociative subtype PTSD indentified structural aberrations in regions subserving the processing and regulation of emotional arousal. These might constitute characteristic biomarkers for the dissociative subtype PTSD.
Background and hypothesis Following the first episode of psychosis, some patients develop poor so... more Background and hypothesis Following the first episode of psychosis, some patients develop poor social and occupational outcomes, while others display a pattern of preserved functioning. Evidence from preclinical, genetic, and biochemical studies suggest a role for high oxidative stress in poor functional outcomes among patients. The measurement of intracortical glutathione (GSH) using magnetic resonance spectroscopy (MRS) enables investigating the relationship between central antioxidant tone and functional outcomes at the time of first-episode psychosis (FEP). We hypothesized that patients with higher central antioxidant tone at first presentation will have better functional outcomes in early stages of illness. Study design We scanned 57 patients with FEP and 30 matched healthy controls and estimated GSH resonance using 7-Tesla MRS. We minimized the confounding effects of illness chronicity, long-term treatment exposure, and metabolic complications by recruiting patients with <2 weeks of lifetime antipsychotic exposure on average and followed up this cohort for the next 1 year to determine functional outcomes. Study results Patients who achieved employment/education or training status (EET) in the first year, had higher GSH at the baseline than healthy controls. Social and occupational functioning assessment scale (SOFAS) scores were also significantly higher in patients with higher GSH levels at the outset, after adjusting for various confounds including baseline SOFAS. Patients who were not in EET did not differ from healthy subjects in their GSH levels. Conclusion Our observations support a key role for the central antioxidant tone in the functional outcomes of early psychosis.
Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare life-threatening disease cau... more Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare life-threatening disease caused by enzyme inhibition or clearance of ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type 1 repeats 13), which leads to platelet aggregation in the microvasculature. 1 The role of ADAMTS13, also known as von Willebrand factor cleaving protease, is to break down ultra-large von Willebrand factor multimers. During an acute iTTP episode,
Despite the known benefits of data‐driven approaches, the lack of approaches for identifying func... more Despite the known benefits of data‐driven approaches, the lack of approaches for identifying functional neuroimaging patterns that capture both individual variations and inter‐subject correspondence limits the clinical utility of rsfMRI and its application to single‐subject analyses. Here, using rsfMRI data from over 100k individuals across private and public datasets, we identify replicable multi‐spatial‐scale canonical intrinsic connectivity network (ICN) templates via the use of multi‐model‐order independent component analysis (ICA). We also study the feasibility of estimating subject‐specific ICNs via spatially constrained ICA. The results show that the subject‐level ICN estimations vary as a function of the ICN itself, the data length, and the spatial resolution. In general, large‐scale ICNs require less data to achieve specific levels of (within‐ and between‐subject) spatial similarity with their templates. Importantly, increasing data length can reduce an ICN's subject‐le...
Background: Recent advances in data-driven computational approaches have been helpful in devising... more Background: Recent advances in data-driven computational approaches have been helpful in devising tools to objectively diagnose psychiatric disorders. However, current machine learning studies limited to small homogeneous samples, different methodologies, and different imaging collection protocols, limit the ability to directly X. Zhu et al.
Single-voxel proton magnetic resonance spectroscopy (SV 1H-MRS) is an in vivo noninvasive imaging... more Single-voxel proton magnetic resonance spectroscopy (SV 1H-MRS) is an in vivo noninvasive imaging technique used to detect neurotransmitters and metabolites. It enables repeated measurements in living participants to build explanatory neurochemical models of psychiatric symptoms and testing of therapeutic approaches.
Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare life-threatening disease cau... more Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare life-threatening disease caused by enzyme inhibition or clearance of ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type 1 repeats 13), which leads to platelet aggregation in the microvasculature. 1 The role of ADAMTS13, also known as von Willebrand factor cleaving protease, is to break down ultra-large von Willebrand factor multimers. During an acute iTTP episode,
Patients with CM-TMA, despite remission, have significant white matter changes on MRI and lower s... more Patients with CM-TMA, despite remission, have significant white matter changes on MRI and lower scores on neurocognitive testing.
ObjectiveOne factor potentially contributing to the heterogeneity of previous results on structur... more ObjectiveOne factor potentially contributing to the heterogeneity of previous results on structural grey matter alterations in adult participants suffering from post‐traumatic stress disorder (PTSD) is the varying levels of dissociative symptomatology. The aim of this study was therefore to test whether the recently defined dissociative subtype of PTSD characterized by symptoms of depersonalization and derealization is characterized by specific differences in volumetric brain morphology.MethodWhole‐brain MRI data were acquired for 59 patients with PTSD. Voxel‐based morphometry was carried out to test for group differences between patients classified as belonging (n = 15) vs. not belonging (n = 44) to the dissociative subtype of PTSD. The correlation between dissociation (depersonalization/derealization) severity and grey matter volume was computed.ResultsPatients with PTSD classified as belonging to the dissociative subtype exhibited greater grey matter volume in the right precentral and fusiform gyri as well as less volume in the right inferior temporal gyrus. Greater dissociation severity was associated with greater volume in the right middle frontal gyrus.ConclusionThe results of this first whole‐brain investigation of specific grey matter volume in dissociative subtype PTSD indentified structural aberrations in regions subserving the processing and regulation of emotional arousal. These might constitute characteristic biomarkers for the dissociative subtype PTSD.
Background and hypothesis Following the first episode of psychosis, some patients develop poor so... more Background and hypothesis Following the first episode of psychosis, some patients develop poor social and occupational outcomes, while others display a pattern of preserved functioning. Evidence from preclinical, genetic, and biochemical studies suggest a role for high oxidative stress in poor functional outcomes among patients. The measurement of intracortical glutathione (GSH) using magnetic resonance spectroscopy (MRS) enables investigating the relationship between central antioxidant tone and functional outcomes at the time of first-episode psychosis (FEP). We hypothesized that patients with higher central antioxidant tone at first presentation will have better functional outcomes in early stages of illness. Study design We scanned 57 patients with FEP and 30 matched healthy controls and estimated GSH resonance using 7-Tesla MRS. We minimized the confounding effects of illness chronicity, long-term treatment exposure, and metabolic complications by recruiting patients with <2 weeks of lifetime antipsychotic exposure on average and followed up this cohort for the next 1 year to determine functional outcomes. Study results Patients who achieved employment/education or training status (EET) in the first year, had higher GSH at the baseline than healthy controls. Social and occupational functioning assessment scale (SOFAS) scores were also significantly higher in patients with higher GSH levels at the outset, after adjusting for various confounds including baseline SOFAS. Patients who were not in EET did not differ from healthy subjects in their GSH levels. Conclusion Our observations support a key role for the central antioxidant tone in the functional outcomes of early psychosis.
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Papers by Jean Théberge