Over the past decade, theta-burst stimulation (TBS) has become a focus of interest in neurostimulatory research. Compared to conventional repetitive transcranial magnetic stimulation (rTMS), TBS produces more robust changes in cortical excitability (CE). There is also some evidence of an analgesic effect of the method. Previously published studies have suggested that different TBS parameters elicit opposite effects of TBS on CE. While intermittent TBS (iTBS) facilitates CE, continuous TBS (cTBS) attenuates it. However, prolonged TBS (pTBS) with twice the number of stimuli produces the opposite effect. In a double-blind, placebo-controlled, cross-over study with healthy subjects (
n
= 24), we investigated the effects of various pTBS (cTBS, iTBS, and placebo TBS) over the right motor cortex on CE and pain perception. Changes in resting motor thresholds (RMTs) and absolute motor-evoked potential (MEP) amplitudes were assessed before and at two time-points (0–5 min; 40–45 min) after pTBS. Tactile and thermal pain thresholds were measured before and 5 min after application. Compared to the placebo, prolonged cTBS (pcTBS) transiently increased MEP amplitudes, while no significant changes were found after prolonged iTBS. However, the facilitation of CE after pcTBS did not induce a parallel analgesic effect. We confirmed that pcTBS with twice the duration converts the conventional inhibitory effect into a facilitatory one. Despite the short-term boost of CE following pcTBS, a corresponding analgesic effect was not demonstrated. Therefore, the results indicate a more complex regulation of pain, which cannot be explained entirely by the modulation of excitability.
ObjectiveTranscranial direct-current stimulation (tDCS), a relatively new neuromodulation approach, provides some evidence of an antidepressant effect. This randomized, 4-week, double-blind study with 8-week, open-label, follow-up compared the efficacy and tolerability of left anodal tDCS with venlafaxine ER (VNF) in the treatment of depression and prevention of early relapse.MethodsSubjects (n = 57) received tDCS (2 mA, 20 sessions, 30 mins) plus placebo (n = 29) or VNF plus sham tDCS (n = 28). Responders to both interventions entered the open-label follow-up. The primary outcome was score change in the Montgomery–Åsberg Depression Rating Scale (MADRS) at week 4 of the study. Secondary outcomes were response, remission, dropout rates and relapse rates within the follow-up.The mean change in the MADRS score from baseline to week for patients treated with tDCS was 7.69 (95% CI, 5.09–10.29) points and 9.64 (95% CI, 6.20–13.09) points for patients from the VNF group, a nonsignificant difference (1.95, 95% CI −2.25–6.16; t (55) = 0.93, p= 0.36, Cohen´s d = 0.24). There were no significant between-group differences in the MADRS scores from baseline to endpoint (intention-to-treat analysis). The response/remission rate for tDCS (24%/17%) and VNF (43%/32%) as well as the dropout rate (tDCS/VNF; 6/6) did not differ significantly between groups. In the follow-up, relapse (tDCS/VNF; 1/2) and dropout (tDCS/VNF; 2/3) rates were low and comparable.
LimitationsA relatively small sample size and short duration of the antidepressant treatment; no placebo arm.ConclusionOverall, this study found a similar efficacy of tDCS and VNF in the acute treatment of depression and prevention of early relapse. The real clinical usefulness of tDCS and its optimal parameters in the treatment of depression should be further validated.
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