Original articleEvidence for Impaired Cortical Inhibition in Patients with Unipolar Major Depression
Section snippets
Patients and Healthy Control Subjects
The study was approved by the Ethics committee of the Benjamin Franklin University Hospital of the Free University of Berlin. Inpatients and outpatients with a major depressive episode meeting the DSM-IV criteria were recruited from the Department of Psychiatry, Free University of Berlin. Out of a larger sample of 84 patients, 20 were free of antidepressants, anticonvulsants, mood stabilizers, or benzodiazepine treatment for at least 4 weeks due to intolerance or nonresponse. These patients
Subjects
Subject demographics are given in Table 1. Patients and volunteers did not differ in demographic variables.
Amplitudes of Motor Evoked Potentials
Mean amplitudes of 10 motor evoked potentials were 1.2 ± .4 mV at baseline and 1.3 ± .3 mV after termination of the measurements of motor cortical excitability.
Motor Threshold
Motor threshold of the right hemisphere was lower in depressed patients compared with normal volunteers, but left hemisphere MT did not differ between the groups (see Table 2,Figure 1). There was an interaction between group and
Discussion
Our results demonstrate that medication-free patients with major depression have significant changes in motor cortical inhibition compared with healthy volunteers, as measured with TMS. Our findings of reduced cortical silent period and intracortical inhibition are consistent with the hypothesis of a contribution of central inhibitory circuits in the pathophysiology of depressive symptoms supported by previous animal, neurochemical, and neuroimaging studies. The question remains, however,
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