Deep brain stimulation (DBS) to the nucleus accumbens (NAcc-DBS) was associated with antidepressant, anxiolytic, and procognitive effects in a small sample of patients suffering from treatment-resistant depression (TRD), followed over 1 year. Results of long-term follow-up of up to 4 years of NAcc-DBS are described in a group of 11 patients. Clinical effects, quality of life (QoL), cognition, and safety are reported. Eleven patients were stimulated with DBS bilateral to the NAcc. Main outcome measures were clinical effect (Hamilton Depression Rating Scale, Montgomery-Asperg Rating Scale of Depression, and Hamilton Anxiety Scale) QoL (SF-36), cognition and safety at baseline, 12 months (n ¼ 11), 24 months (n ¼ 10), and last follow-up (maximum 4 years, n ¼ 5). Analyses were performed in an intent-to-treat method with last observation carried forward, thus 11 patients contributed to each point in time. In all, 5 of 11 patients (45%) were classified as responders after 12 months and remained sustained responders without worsening of symptoms until last follow-up after 4 years. Both ratings of depression and anxiety were significantly reduced in the sample as a whole from first month of NAcc-DBS on. All patients improved in QoL measures. One non-responder committed suicide. No severe adverse events related to parameter change were reported. First-time, preliminary long-term data on NAcc-DBS have demonstrated a stable antidepressant and anxiolytic effect and an amelioration of QoL in this small sample of patients suffering from TRD. None of the responders of first year relapsed during the observational period (up to 4 years).
Short- and long-term antidepressant effects of deep brain stimulation (DBS) in treatment-resistant depression (TRD) have been demonstrated for several brain targets in open-label studies. For two stimulation targets, pivotal randomized trials have been conducted; both failed a futility analysis. We assessed efficacy and safety of DBS of the supero-lateral branch of the medial forebrain bundle (slMFB) in a small Phase I clinical study with a randomized-controlled onset of stimulation in order to obtain data for the planning of a large RCT. Sixteen patients suffering from TRD received DBS of the slMFB and were randomized to sham or real stimulation for the duration of 2 months after implantation. Primary outcome measure was mean reduction in Montgomery–Åsberg Depression Rating Scale (MADRS) during 12 months of DBS (timeline analysis). Secondary outcomes were the difference in several clinical measures between sham and real stimulation at 8 weeks and during stimulation phases. MADRS ratings decreased significantly from 29.6 (SD +/− 4) at baseline to 12.9 (SD +/− 9) during 12 months of DBS (mean MADRS, n = 16). All patients reached the response criterion, most patients (n = 10) responded within a week; 50% of patients were classified as remitters after 1 year of stimulation. The most frequent side effect was transient strabismus. Both groups (active/sham) demonstrated an antidepressant micro-lesioning effect but patients had an additional antidepressant effect after initiation of stimulation. Both rapid onset and stability of the antidepressant effects of slMFB-DBS were demonstrated as in our previous pilot study. Given recent experiences from pivotal trials in DBS for MDD, we believe that slow, careful, and adaptive study development is germane. After our exploratory study and a large-scale study, we conducted this gateway trial in order to better inform planning of the latter. Important aspects for the planning of RCTs in the field of DBS for severe and chronic diseases are discussed including meaningful phases of intra-individual and between-group comparisons and timeline instead of single endpoint analyses.
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