Open Access Research article

Different patterns of cortical excitability in major depression and vascular depression: a transcranial magnetic stimulation study

Carmen Concerto1, Giuseppe Lanza2, Mariagiovanna Cantone2, Manuela Pennisi3, Daniela Giordano4, Concetto Spampinato4, Riccardo Ricceri2, Giovanni Pennisi2*, Eugenio Aguglia1 and Rita Bella2

Author Affiliations

1 Unit of Psychiatry, Department of Clinical and Molecular Biomedicine, University of Catania, Via Santa Sofia, 78-95123 Catania, Italy

2 Department “G.F. Ingrassia”, Section of Neurosciences, University of Catania, Via Santa Sofia, 78-95123 Catania, Italy

3 Department of Chemistry, University of Catania, Viale Andrea Doria 6, 95125 Catania, Italy

4 Department of Electrical, Electronics and Informatics Engineering, University of Catania, Viale Andrea Doria 6, 95125 Catania, Italy

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BMC Psychiatry 2013, 13:300  doi:10.1186/1471-244X-13-300

Published: 9 November 2013

Abstract

Background

Clinical and functional studies consider major depression (MD) and vascular depression (VD) as different neurobiological processes. Hypoexcitability of the left frontal cortex to transcranial magnetic stimulation (TMS) is frequently reported in MD, whereas little is known about the effects of TMS in VD. Thus, we aimed to assess and compare motor cortex excitability in patients with VD and MD.

Methods

Eleven VD patients, 11 recurrent drug-resistant MD patients, and 11 healthy controls underwent clinical, neuropsychological and neuroimaging evaluations in addition to bilateral resting motor threshold, cortical silent period, and paired-pulse TMS curves of intracortical excitability. All patients continued on psychotropic drugs, which were unchanged throughout the study.

Results

Scores on one of the tests evaluating frontal lobe abilities (Stroop Color-Word interference test) were worse in patients compared with controls. The resting motor threshold in patients with MD was significantly higher in the left hemisphere compared with the right (p < 0.05), and compared with the VD patients and controls. The cortical silent period was bilaterally prolonged in MD patients compared with VD patients and controls, with a statistically significant difference in the left hemisphere (p < 0.01). No differences were observed in the paired-pulse curves between patients and controls.

Conclusions

This study showed distinctive patterns of motor cortex excitability between late-onset depression with subcortical vascular disease and early-onset recurrent drug resistant MD. The data provide a TMS model of the different processes underlying VD and MD. Additionally, our results support the “Vascular depression hypothesis” at the neurophysiological level, and confirm the inter-hemispheric asymmetry to TMS in patients with MD. We were unable to support previous findings of impaired intracortical inhibitory mechanisms to TMS in patients with MD, although a drug-induced effect on our results cannot be excluded. This study may aid the understanding of the pathogenetic differences underlying the clinical spectrum of depressive disorders.

Keywords:
Late-onset depression; Cortical excitability; Subcortical vascular disease; Neuroplasticity