Background & Aims
Repeated transcranial direct current stimulation (tDCS) over the left primary motor cortex (l-M1) [1] and regular mindfulness meditation (MM) practice [2] have yielded therapeutic benefits in fibromyalgia (FM), with observed changes in M1 excitability measured by transcranial magnetic stimulation (TMS) [3, 4]. Pairing MM and tDCS has shown synergistic effects in both healthy and diseased groups [5]. In our pilot study, FM patients reported better quality of life [QOL] following combined MM and anodal tDCS over the l-M1 than control groups, without any group differences for pain relief and associated symptoms [6]. In this study, we tested the therapeutic effects of this combined therapy in a larger group of patients trained in MM, with the main objective of potentiating the effectiveness of the classical tDCS protocol in FM by pairing it with MM. We also aimed to underpin the mechanisms of the combined therapy using TMS measures of cortical excitability.
Methods
We designed a formal 4-week mindfulness intervention tailored for FM to teach participants to meditate. Following the mindfulness training, the 44 included participants (30-72 years, 41 women) were equally and randomly allocated to receive 10 daily 20-min sessions of 2 mA anodal tDCS over the l-M1 paired with MM or sham tDCS combined with MM using a triple-blinded design. Participants rated their pain intensity twice daily on the numerical rating scale throughout the study. The QOL, sleep quality, psychological impairment, mood, and mindfulness levels were evaluated via a self-reported battery of questionnaires. M1 excitability was determined via input-output (I-O) curves using single-pulse TMS and paired-pulse intracortical TMS measures. We collected TMS and questionnaire data post-mindfulness training, immediately and 4 weeks after the combined treatment. Data was analyzed using mixed model ANOVAs.
Results
The groups were age- and sex-matched. Participants reported higher mindfulness levels post mindfulness training than at baseline (p < 0.001, d = 2.54), proving the effectiveness of the brief MM training. Both groups showed an acute reduction in pain, negative mood, depressiveness, and stress and improvement in QOL and sleep quality post-combined therapy, with medium effect sizes. However, no group effect or group*time interaction was observed (p = 0.036). We found a medium group*time interaction for corticospinal activity, assessed by the slope of the I-O curve. Further exploration of the significant interaction did not show any statistically significant pairwise comparisons (p > 0.05). No significant effects were found for any paired-pulse measure. Mindfulness levels increased with a large effect size (p < 0.001) in both groups up to one month post stimulation.
Conclusions
Our findings failed to replicate the ability of combined anodal tDCS and MM to improve clinical outcomes in chronic pain, compared to sham [6, 7, 8]. Unlike these previous studies, we included an effective mindfulness training to teach the participants to meditate prior to stimulation. The mechanistic effects of the intervention using TMS was inconclusive, due to lack of significant results. The non-specific main effect of time in pain, QOL and associated symptoms, with a large significant increase in mindfulness over time could hint at a potential ‘mindfulness effect’, in line with previous studies showing longer MM practice results in greater therapeutic benefits in FM [2, 9]. Therefore, the combination of MM and tDCS must be reconsidered as a motive to optimize tDCS treatment in FM. Future studies should include monotherapy control groups and the target for tDCS should be personalized for patients, based on predominant symptomology.
References
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Presenting Author
Perianen Ramasawmy
Poster Authors
Perianen Ramasawmy
M.Sc.
University Medical Center Göttingen
Lead Author
Olga Lucia Gamboa Arana
School of Psychology, University of Sydney
Lead Author
Frank PETZKE
Prof. Dr
Department of Anesthesiology, University Hospital Medical Center, Gottingen, Germany
Lead Author
Andrea Antal
Dept. of Neurology, University Medical Center Göttingen
Lead Author
Topics
- Treatment/Management: Interventional Therapies – Neuromodulation