title: Prolonged cortical silent period among drug-naive subjects at ultra-high risk of psychosis.
abstract: BACKGROUND
  Deficits in gamma-aminobutyric acid (GABA) inhibitory neurotransmission have been associated with pathophysiological mechanisms underlying schizophrenia. However, little is known about whether these deficits occur before or after the onset of psychosis.
  
  
  METHODS
  We recruited 16 drug-naive subjects at ultra-high risk of psychosis (UHR), 17 schizophrenia patients and 28 healthy controls. Cortical inhibition was determined using transcranial magnetic stimulation (TMS) over the left primary motor cortex. TMS markers such as short-interval cortical inhibition (SICI), cortical silent period (CSP) and intracortical facilitation (ICF) were obtained from each subject. While SICI can reflect GABA type A (GABAA) mediated inhibition, CSP is thought to indicate GABA type B (GABAB) mediated inhibitory circuits.
  
  
  RESULTS
  As compared with healthy controls, UHR subjects showed a prolonged CSP with no change in SICI, whereas schizophrenia patients demonstrated both a prolonged CSP and a reduced SICI. No group differences were found for ICF. CSP in schizophrenia patients also had a positive correlation with positive symptom score of the positive and negative symptom scale (PANSS).
  
  
  CONCLUSIONS
  Cortical inhibitory deficits among UHR subjects were relatively limited compared to those among schizophrenia patients. Alterations might occur in some subgroup of GABA-mediated neurotransmitter systems before the onset of psychosis, while alterations in both GABAA and GABAB networks might contribute to full-blown psychosis.
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China; Department of EEG and Imaging, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China; Department of EEG and Imaging, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Tianhong
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Bradley
authors.initials: B
authors.lastname: Edelman
authors.affiliation: Department of EEG and Imaging, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Botao
authors.initials: B
authors.lastname: Zeng
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of EEG and Imaging, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Kaiming
authors.initials: K
authors.lastname: Zhuo
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Zhenying
authors.initials: Z
authors.lastname: Qian
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Huiru
authors.initials: H
authors.lastname: Cui
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Yikang
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China; Department of EEG and Imaging, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China.
authors.forename: Chunbo
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Psychiatry, Yangpu Hospital, Medical School of Tongji University, Shanghai 200090, PR China. Electronic address: ydh@tongji.edu.cn.
authors.forename: Dehua
authors.initials: D
authors.lastname: Yu
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China; Department of EEG and Imaging, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, PR China. Electronic address: jijunwang27@gmail.com.
authors.forename: Jijun
authors.initials: J
authors.lastname: Wang
mesh_terms: D000328:Adult; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D009433:Neural Inhibition / Q000502:physiology; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000453:epidemiology / Q000503:physiopathology*; D012306:Risk; D012559:Schizophrenia / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
keywords: Cortical inhibition; Cortical silent period; Schizophrenia; Short-interval cortical inhibition; Ultra-high risk of psychosis