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Evidence for increased motor cortical facilitation and decreased inhibition in atypical depression
Author(s) -
Veronezi B. P.,
Moffa A. H.,
Carvalho A. F.,
Galhardoni R.,
Simis M.,
Benseñor I. M.,
Lotufo P. A.,
MachadoVieira R.,
Daskalakis Z. J.,
Brui A. R.
Publication year - 2016
Publication title -
acta psychiatrica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.849
H-Index - 146
eISSN - 1600-0447
pISSN - 0001-690X
DOI - 10.1111/acps.12565
Subject(s) - transcranial magnetic stimulation , major depressive disorder , psychology , glutamate receptor , glutamatergic , neuroscience , facilitation , silent period , motor cortex , depression (economics) , antidepressant , medicine , stimulation , receptor , cognition , hippocampus , economics , macroeconomics
Objective Major depressive disorder ( MDD ) is a clinically heterogeneous condition. However, the role of cortical glutamate and gamma‐aminobutyric acid ( GABA ) receptor‐mediated activity, implicated in MDD pathophysiology, has not been explored in different MDD subtypes. Our aim was to assess the atypical and melancholic depression subtypes regarding potential differences in GABA and glutamate receptor‐mediated activity through established transcranial magnetic stimulation ( TMS ) neurophysiological measures from the motor cortex. Method We evaluated 81 subjects free of antidepressant medication, including 21 healthy controls and 20 patients with atypical, 20 with melancholic, and 20 with undifferentiated MDD . Single and paired‐pulse TMS paradigms were used to evaluate intracortical facilitation ( ICF ), cortical silent period ( CSP ), and short intracortical inhibition ( SICI ), which index glutamate, GABA B receptor‐, and GABA A receptor‐mediated activity respectively. Results Patients with MDD demonstrated significantly decreased mean CSP values than healthy controls (Cohen's d = 0.22–0.3, P < 0.01 for all comparisons). Atypical depression presented a distinct cortical excitability pattern of decreased cortical inhibition and increased cortical facilitation, that is, an increased mean ICF and SICI ratios than other depression subtypes ( d = 0.22–0.33, P < 0.01 for all comparisons). Conclusion Different MDD subtypes may demonstrate different neurophysiology in relation to GABA A and glutamatergic activity. TMS as an investigational tool might be useful to distinguish between different MDD subtypes.