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Mehta DD, Siddiqui S, Ward HB, Steele VR, Pearlson GD, George TP. Functional and structural effects of repetitive transcranial magnetic stimulation (rTMS) for the treatment of auditory verbal hallucinations in schizophrenia: A systematic review. Schizophr Res 2024; 267:86-98. [PMID: 38531161 DOI: 10.1016/j.schres.2024.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 02/26/2024] [Accepted: 03/15/2024] [Indexed: 03/28/2024]
Abstract
BACKGROUND Auditory verbal hallucinations (AVH) are a disabling symptom for people with schizophrenia (SCZ), and do not always respond to antipsychotics. Repetitive transcranial magnetic stimulation (rTMS) has shown efficacy for medication-refractory AVH, though the underlying neural mechanisms by which rTMS produces these effects remain unclear. This systematic review evaluated the structural and functional impact of rTMS for AVH in SCZ, and its association with clinical outcomes. METHODS A systematic search was conducted in Medline, PsychINFO, and PubMed using terms for four key concepts: AVH, SCZ, rTMS, neuroimaging. Using PRISMA guidelines, 18 studies were identified that collected neuroimaging data of an rTMS intervention for AVH in SCZ. Risk of bias assessments was conducted. RESULTS Low frequency (<5 Hz) rTMS targeting left hemispheric language processing regions may normalize brain abnormalities in AVH patients at structural, functional, electrophysiological, and topological levels, with concurrent symptom improvement. Amelioration of aberrant neural activity in frontotemporal networks associated with speech and auditory processing was commonly observed, as well as in cerebellar and emotion regulation regions. Neuroimaging analyses identified neural substrates with direct correlations to post-rTMS AVH severity, propounding their use as therapeutic targets. DISCUSSION Combined rTMS-neuroimaging highlights the multidimensional alterations of rTMS on brain activity and structure in treatment-resistant AVH, which may be used to develop more efficacious therapies. Larger randomized, sham-controlled studies are needed. Future studies should explore alternate stimulation targets, investigate the neural effects of high-frequency rTMS and evaluate long-term neuroimaging outcomes.
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Affiliation(s)
- Dhvani D Mehta
- Institute of Medical Sciences, Temerty Faculty of Medicine, University of Toronto, Canada; Department of Psychiatry, Vanderbilt University, Nashville, TN, USA; Hartford Hospital and Department of Psychiatry and Behavioural Sciences, Yale University, New Haven, CT, USA; Department of Psychiatry, University of Toronto, Canada; Addictions Division and Institute for Mental Health Policy and Research, Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada.
| | - Salsabil Siddiqui
- Institute of Medical Sciences, Temerty Faculty of Medicine, University of Toronto, Canada; Department of Psychiatry, Vanderbilt University, Nashville, TN, USA; Hartford Hospital and Department of Psychiatry and Behavioural Sciences, Yale University, New Haven, CT, USA; Department of Psychiatry, University of Toronto, Canada; Addictions Division and Institute for Mental Health Policy and Research, Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada
| | - Heather B Ward
- Institute of Medical Sciences, Temerty Faculty of Medicine, University of Toronto, Canada; Department of Psychiatry, Vanderbilt University, Nashville, TN, USA; Hartford Hospital and Department of Psychiatry and Behavioural Sciences, Yale University, New Haven, CT, USA; Department of Psychiatry, University of Toronto, Canada; Addictions Division and Institute for Mental Health Policy and Research, Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada
| | - Vaughn R Steele
- Institute of Medical Sciences, Temerty Faculty of Medicine, University of Toronto, Canada; Department of Psychiatry, Vanderbilt University, Nashville, TN, USA; Hartford Hospital and Department of Psychiatry and Behavioural Sciences, Yale University, New Haven, CT, USA; Department of Psychiatry, University of Toronto, Canada; Addictions Division and Institute for Mental Health Policy and Research, Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada
| | - Godfrey D Pearlson
- Institute of Medical Sciences, Temerty Faculty of Medicine, University of Toronto, Canada; Department of Psychiatry, Vanderbilt University, Nashville, TN, USA; Hartford Hospital and Department of Psychiatry and Behavioural Sciences, Yale University, New Haven, CT, USA; Department of Psychiatry, University of Toronto, Canada; Addictions Division and Institute for Mental Health Policy and Research, Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada
| | - Tony P George
- Institute of Medical Sciences, Temerty Faculty of Medicine, University of Toronto, Canada; Department of Psychiatry, Vanderbilt University, Nashville, TN, USA; Hartford Hospital and Department of Psychiatry and Behavioural Sciences, Yale University, New Haven, CT, USA; Department of Psychiatry, University of Toronto, Canada; Addictions Division and Institute for Mental Health Policy and Research, Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada.
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Galdino LB, Fernandes T, Schmidt KE, Santos NA. Altered brain connectivity during visual stimulation in schizophrenia. Exp Brain Res 2022; 240:3327-3337. [PMID: 36322165 DOI: 10.1007/s00221-022-06495-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 10/20/2022] [Indexed: 11/23/2022]
Abstract
Schizophrenia (SCZ) can be described as a functional dysconnectivity syndrome that affects brain connectivity and circuitry. However, little is known about how sensory stimulation modulates network parameters in schizophrenia, such as their small-worldness (SW) during visual processing. To address this question, we applied graph theory algorithms to multi-electrode EEG recordings obtained during visual stimulation with a checkerboard pattern-reversal stimulus. Twenty-six volunteers participated in the study, 13 diagnosed with schizophrenia (SCZ; mean age = 38.3 years; SD = 9.61 years) and 13 healthy controls (HC; mean age = 28.92 years; SD = 12.92 years). The visually evoked potential (VEP) showed a global amplitude decrease (p < 0.05) for SCZ patients as opposed to HC but no differences in latency (p > 0.05). As a signature of functional connectivity, graph measures were obtained from the Magnitude-Squared Coherence between signals from pairs of occipital electrodes, separately for the alpha (8-13 Hz) and low-gamma (36-55 Hz) bands. For the alpha band, there was a significant effect of the visual stimulus on all measures (p < 0.05) but no group interaction between SCZ and HZ (p > 0.05). For the low-gamma spectrum, both groups showed a decrease of Characteristic Path Length (L) during visual stimulation (p < 0.05), but, contrary to the HC group, only SCZ significantly lowered their small-world (SW) connectivity index during visual stimulation (SCZ p < 0.05; HC p > 0.05). This indicates dysconnectivity of the functional network in the low-gamma band of SCZ during stimulation, which might indirectly reflect an altered ability to react to new sensory input in patients. These results provide novel evidence about a possible electrophysiological signature of the global deficits revealed by the application of graph theory onto electroencephalography in schizophrenia.
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Affiliation(s)
- Lucas B Galdino
- Laboratory of Perception, Neurosciences and Behaviour, Department of Psychology, Federal University of Paraiba, João Pessoa, Brazil. .,Neurobiology of Vision Lab, Brain Institute (ICe), Federal University of Rio Grande do Norte, Natal, Brazil.
| | - Thiago Fernandes
- Laboratory of Perception, Neurosciences and Behaviour, Department of Psychology, Federal University of Paraiba, João Pessoa, Brazil
| | - Kerstin E Schmidt
- Neurobiology of Vision Lab, Brain Institute (ICe), Federal University of Rio Grande do Norte, Natal, Brazil
| | - Natanael A Santos
- Laboratory of Perception, Neurosciences and Behaviour, Department of Psychology, Federal University of Paraiba, João Pessoa, Brazil
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