title: Cortical excitability in cocaine-dependent patients: a replication and extension of TMS findings.
abstract: Cortical excitability can be assessed by transcranial magnetic stimulation (TMS). Previously we observed that TMS motor threshold (MT) was elevated in abstinent cocaine-dependent subjects. In the current study we aimed at replicating our initial finding, exploring other TMS-based measures of excitability, and examining association with personality characteristics. Nineteen cocaine-dependent and 12 healthy control subjects were examined. Resting and activated motor thresholds (RMT and AMT) and duration of the cortical silent period (CSP) were examined. The Cocaine Experience Questionnaire (CEQ) was administered to assess cocaine-induced psychotic symptoms. The relationship between Minnesota Multiphasic Personality Inventory (MMPI) scales and cortical excitability measures was also examined. AMT was significantly elevated in cocaine-dependent subjects on both hemispheres. RMT was also significantly elevated on the right hemisphere. No CSP changes were noted. Patients with cocaine-induced paranoia had longer CSPs on the right hemisphere compared to subjects reporting no paranoid experiences. The patients displayed significantly elevated scores on several MMPI scales, though the scale scores did not correlate with cortical excitability measures. These data support our initial finding of decreased cortical excitability in abstinent cocaine-dependent subjects. We interpret this finding as a compensatory mechanism against the stimulating and epileptogenic effects of cocaine.
authors.affiliation: Department of Psychiatry, c/o VA-Connecticut Healthcare System, Yale University School of Medicine, 950 Campbell Avenue, 116A West Haven, CT 06516, USA. nash.boutros@yale.edu
authors.forename: Nashaat N
authors.initials: NN
authors.lastname: Boutros
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Lisanby
authors.forename: Dennis
authors.initials: D
authors.lastname: McClain-Furmanski
authors.forename: Glen
authors.initials: G
authors.lastname: Oliwa
authors.forename: Diane
authors.initials: D
authors.lastname: Gooding
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Kosten
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000187:drug effects* / Q000503:physiopathology*; D003042:Cocaine / Q000009:adverse effects*; D019970:Cocaine-Related Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D008950:MMPI; D008280:Magnetics / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000187:drug effects / Q000503:physiopathology; D010554:Personality Disorders / Q000175:diagnosis / Q000453:epidemiology; D012886:Skull; D011795:Surveys and Questionnaires
chemical_list: D003042:Cocaine