Article

Effects of 12 Months of Vagus Nerve Stimulation in Treatment-Resistant Depression: A Naturalistic Study

Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
Biological Psychiatry (Impact Factor: 10.25). 10/2005; 58(5):355-63. DOI: 10.1016/j.biopsych.2005.05.024
Source: PubMed

ABSTRACT The need for effective, long-term treatment for recurrent or chronic, treatment-resistant depression is well established.
This naturalistic follow-up describes outpatients with nonpsychotic major depressive (n = 185) or bipolar (I or II) disorder, depressed phase (n = 20) who initially received 10 weeks of active (n = 110) or sham vagus nerve stimulation (VNS) (n = 95). The initial active group received another 9 months, while the initial sham group received 12 months of VNS. Participants received antidepressant treatments and VNS, both of which could be adjusted.
The primary analysis (repeated measures linear regression) revealed a significant reduction in 24-item Hamilton Rating Scale for Depression (HRSD(24)) scores (average improvement, .45 points [SE = .05] per month (p < .001). At exit, HRSD(24) response rate was 27.2% (55/202); remission rate (HRSD(24) < or = 9) was 15.8% (32/202). Montgomery Asberg Depression Rating Scale (28.2% [57/202]) and Clinical Global Impression-Improvement (34.0% [68/200]) showed similar response rates. Voice alteration, dyspnea, and neck pain were the most frequently reported adverse events.
These 1-year open trial data found VNS to be well tolerated, suggesting a potential long-term, growing benefit in treatment-resistant depression, albeit in the context of changes in depression treatments. Comparative long-term data are needed to determine whether these benefits can be attributed to VNS.

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    • "Vagus nerve stimulation (VNS) was approved by the U. S. Food and Drug Administration in 2005 and has been frequently used as a treatment option for treatment-resistant depression (TRD) [1] [2] [3] [4]. Its mechanisms of antidepressant action are not fully elucidated; however, its neuromechanisms are based on the direct stimulation of the cervical trunk of the left vagus nerve. "
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    • "With respect to efficacy in depression , a 12-week study comparing severely ill patients who received VNS in addition to the medications they had been receiving did not improve significantly more than those who received sham treatment (Rush et al, 2005a). However, follow-up of those patients who had received VNS and continued receiving such stimulation for an additional 9 months or switching the sham-treated patients to VNS for 12 months indicated a time-dependent increase in efficacy (Rush et al, 2005b). After 12 months of VNS, both response and remission rates were about double those at 3 months. "
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    • "All patients followed the trial protocol as described elsewhere (Rush et al., 2005b). Stimulation parameters at 1 year were the following: signal frequency, 20 Hz; signal on time, 30 s; signal off time, 5 min; current and pulse width as listed in Table 1. "
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