title: Resting electroencephalographic correlates of the clinical response to repetitive transcranial magnetic stimulation: A preliminary comparison between unipolar and bipolar depression.
abstract: BACKGROUND
  Major depressive disorder (MDD) and bipolar disorder (BP) are two different types of mood disorders, sometimes difficult to distinguish from their depressive symptoms, and for which repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex (DLPFC) has been proposed to treat refractory patients. Here we studied whether the electroencephalogram (EEG) at rest could be used to predict the therapeutic response to left DLPFC 10 Hz rTMS, and to which extent BP and MDD patients show similar correlation between the clinical response and the cortical networks at rest.
  
  
  METHODS
  Eight MDD (6 females) and 10 BP patients (6 females) were included. The rTMS therapy consisted of 10 to 20 neuronavigated sessions, with 2000 pulses continuously applied at 120% motor threshold for each session. RTMS sessions at the beginning, middle and end of the therapy were performed while recording EEG signals. EEG spectral power was partitioned using the common physiological frequency bands and was statistically analysed at the scalp level and after cortical source reconstruction.
  
  
  RESULTS
  We found significantly higher power in theta and beta bands in BP patients than in MDD patients, mainly localised in the prefrontal cortex. In addition, responders showed higher power in delta and theta bands in parietal regions and weaker frontal alpha power, when compared to non-responders.
  
  
  CONCLUSIONS
  These preliminary findings on a small cohort suggest that pre-treatment EEG oscillatory patterns may have some predictive value regarding rTMS therapy, both for MDD and BP disorders.
authors.affiliation: EA 4617 Fonctions Cérébrales et Neuromodulation, Grenoble Institut des Neurosciences, Université Joseph Fourier, Grenoble, France.
authors.forename: Agata
authors.initials: A
authors.lastname: Woźniak-Kwaśniewska
authors.affiliation: EA 4617 Fonctions Cérébrales et Neuromodulation, Grenoble Institut des Neurosciences, Université Joseph Fourier, Grenoble, France; Clinique Universitaire de Psychiatrie, Pôle Psychiatrie Neurologie, Centre Hospitalier Universitaire, Grenoble, France.
authors.forename: David
authors.initials: D
authors.lastname: Szekely
authors.affiliation: UMR 5105 UPMF CNRS, Laboratoire Psychologie Neurocognition, Saint Martin d׳Hères, France; UMS IRMaGe, Grenoble, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Harquel
authors.affiliation: Clinique Universitaire de Psychiatrie, Pôle Psychiatrie Neurologie, Centre Hospitalier Universitaire, Grenoble, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Bougerol
authors.affiliation: EA 4617 Fonctions Cérébrales et Neuromodulation, Grenoble Institut des Neurosciences, Université Joseph Fourier, Grenoble, France. Electronic address: Olivier.David@inserm.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: David
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis / Q000503:physiopathology*; D058256:Brain Waves / Q000502:physiology*; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe; D017397:Prefrontal Cortex / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
keywords: Dorso-lateral prefrontal cortex; EEG; Mood disorders; Source localisation; Statistical parametric mapping; rTMS