Evidence for impaired cortical inhibition in patients with unipolar major depression.
BACKGROUND
Several lines of evidence suggest that central cortical inhibitory mechanisms, especially associated with gamma-aminobutyric acid (GABA) neurotransmission, may play a role in the pathophysiology of major depression. Transcranial magnetic stimulation is a useful tool for investigating central cortical inhibitory mechanisms associated with GABAergic neurotransmission in psychiatric and neurological disorders.


METHODS
By means of transcranial magnetic stimulation, different parameters of cortical excitability, including motor threshold, the cortical silent period, and intracortical inhibition/facilitation, were investigated in 20 medication-free depressed patients and 20 age- and gender-matched healthy volunteers.


RESULTS
Silent period and intracortical inhibition were reduced in depressed patients, consistent with a reduced GABAergic tone. Moreover, patients showed a significant hemispheric asymmetry in motor threshold.


CONCLUSIONS
This study provides evidence of reduced GABAergic tone and motor threshold asymmetry in patients with major depression.
Bajbouj
Malek
M
Department of Psychiatry, Charité University Medicine Berlin, Berlin, Germany. malek.bajbouj@charite.de
Lisanby
Sarah H
SH
Lang
Undine E
UE
Danker-Hopfe
Heidi
H
Heuser
Isabella
I
Neu
Peter
P
D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000503:physiopathology*; D004292:Dominance, Cerebral / Q000502:physiology; D004576:Electromyography; D005260:Female; D006225:Hand / Q000294:innervation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D009433:Neural Inhibition / Q000502:physiology*; D012016:Reference Values; D012684:Sensory Thresholds / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology; D050781:Transcranial Magnetic Stimulation; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D005680:gamma-Aminobutyric Acid