title: Investigating Cortical Inhibition in First-Degree Relatives and Probands in Schizophrenia.
abstract: Deficits in GABAergic inhibitory neurotransmission are a reliable finding in schizophrenia (SCZ) patients. Previous studies have reported that unaffected first-degree relatives of patients with SCZ demonstrate neurophysiological abnormalities that are intermediate between probands and healthy controls. In this study, first-degree relatives of patients with SCZ and their related probands were investigated to assess frontal cortical inhibition. Long-interval cortical inhibition (LICI) was measured from the dorsolateral prefrontal cortex (DLPFC) using combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG). The study presents an extended sample of 129 subjects (66 subjects have been previously reported): 19 patients with SCZ or schizoaffective disorder, 30 unaffected first-degree relatives of these SCZ patients, 13 obsessive-compulsive disorder (OCD) patients, 18 unaffected first-degree relatives of these OCD patients and 49 healthy subjects. In the DLPFC, cortical inhibition was significantly decreased in patients with SCZ compared to healthy subjects. First-degree relatives of patients with SCZ showed significantly more cortical inhibition than their SCZ probands. No differences were demonstrated between first-degree relatives of SCZ patients and healthy subjects. Taken together, these findings show that more studies are needed to establish an objective biological marker for potential diagnostic usage in severe psychiatric disorders.
authors.affiliation: Novartis Pharmaceuticals Canada Inc., Dorval, Quebec, Canada.
authors.forename: Natasha
authors.initials: N
authors.lastname: Radhu
authors.affiliation: Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Luis Garcia
authors.initials: LG
authors.lastname: Dominguez
authors.affiliation: Department of Psychiatry, School of Medicine, University of California, San Diego, La Jolla, California, USA.
authors.forename: Tiffany A
authors.initials: TA
authors.lastname: Greenwood
authors.affiliation: Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Faranak
authors.initials: F
authors.lastname: Farzan
authors.affiliation: Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Mawahib O
authors.initials: MO
authors.lastname: Semeralul
authors.affiliation: Frederick W. Thompson Anxiety Disorders Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Richter
authors.affiliation: Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario Canada.
authors.forename: James L
authors.initials: JL
authors.lastname: Kennedy
authors.affiliation: Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Blumberger
authors.affiliation: Division of Neurology, Krembil Research Institute, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Chen
authors.affiliation: Monash Alfred Psychiatry Research Centre, The Alfred and Monash University Central Clinical School, Victoria, Australia.
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fitzgerald
authors.affiliation: Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Zafiris J
authors.initials: ZJ
authors.lastname: Daskalakis
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000378:metabolism / Q000503:physiopathology*; D004569:Electroencephalography; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009433:Neural Inhibition; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D017397:Prefrontal Cortex / Q000503:physiopathology; D012559:Schizophrenia / Q000175:diagnosis / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation