Investigation into the effect of transcranial direct current stimulation on cardiac pacemakers.

BACKGROUND: Studies investigating the therapeutic applications of transcranial direct current stimulation (tDCS) in the treatment of age-related neurodegenerative disease have been promising. However, exclusion criteria for these studies invariably disqualify patients implanted with internal cardiac pacemakers, citing safety concerns. Because the majority of cardiac pacemaker implantees are over 65, this criterion may limit candidacy for tDCS based research and/or treatment of age-related neurodegenerative disease. OBJECTIVE/HYPOTHESIS: We will test the hypothesis that tDCS impacts pacemaker function. Strong electrical potentials, such as those generated by external defibrillators (∼500 V, ∼10 A), are known to occasionally damage pacemaker circuitry and software, but it seems unlikely tDCS would damage a pacemaker because it involves about 1/200th the energy (∼12 V, ∼2 mA) of an external defibrillator. METHODS: We delivered tDCS to seven participants (ages 70-92) with bipolar non-dependent pacemakers and subsequently collected data from the internal memory of the pacemakers to assess the tDCS signal detection, as well as alterations in mode switches, impedance levels, and pacing. Subsequently, similar assessments were carried out in participants who were pacemaker-dependent (ages 89-91). RESULTS: After a review of the recordings, it was found that tDCS had no impact on the non-dependant, as well as the dependent, pacemakers. There were zero mode switches nor any impact on impedance levels. CONCLUSION: Results in this small series of cases found no evidence that tDCS interferes with the function of the pacemakers and suggests tDCS can be delivered to patients equipped with a cardiac pacemaker. Further studies are needed to generalize these results to other pacemakers.

Maximizing the Treatment Benefit of tDCS in Neurodegenerative Anomia.

We evaluated whether transcranial direct current stimulation (tDCS) in two different montages could improve picture naming abilities in participants with anomic Alzheimer Disease or Frontotemporal dementia. METHODS: Utilizing a double-blind cross-over design, twelve participants were trained on picture naming over a series of 10 sessions with 30 min of anodal (2 mA) tDCS stimulation to either the left inferior parietotemporal region (P3), the left dorsolateral prefrontal cortex (F3), or sham stimulation. We evaluated performance on a trained picture naming list, an equivalent novel untrained list, and additional neuropsychological tasks. RESULTS: For trained item picture naming, significantly larger improvement was seen for real stimulation vs. sham stimulation for both the DLPFC and left inferior parieto-temporal stimulation montages at the end of the stimulation sessions. The parieto-temporal montage remained superior to sham 2 weeks poststimulation. Significant improvement vs. sham was also seen for novel "untrained" item picture naming 2 weeks post-stimulation when the parieto-temporal montage was given, whereas no change was observed when the DLPFC montage was given. Finally, comparing groups when they received the parieto-temporal montage, participants with semantic variant Primary Progressive Aphasia (PPA) showed the least improvement for untrained items after their sessions. Scores on the additional neuropsychological tasks were unchanged. CONCLUSION: tDCS stimulation has promise as a treatment for individuals with anomia arising from neurodegenerative disease, but its effectiveness can vary depending on the training given, the montage location used, as well as a participants' diagnosis.

Inferior parietal transcranial direct current stimulation with training improves cognition in anomic Alzheimer's disease and frontotemporal dementia.

INTRODUCTION: We evaluated whether transcranial direct current stimulation (tDCS) can improve picture-naming abilities in subjects with anomic Alzheimer or frontotemporal dementias. METHODS: Using a double-blind crossover design, 10 participants were trained on picture naming over a series of 10 sessions with either 30 minutes of anodal (2 mA) tDCS stimulation to the left inferior parieto-temporal region (P3) or sham stimulation. We evaluated performance on a trained picture-naming list, an equivalent untrained list, and additional neuropsychological tasks. RESULTS: Participants improved significantly more receiving real stimulation rather than sham stimulation (40% vs. 19%, P < .01), lasting at least 2 weeks after stimulation. Furthermore, these participants showed a small increase for untrained picture-naming items and digit span when they received real stimulation but a decrease when sham stimulation was received. DISCUSSION: tDCS stimulation has promise as a treatment for anomia in demented individuals and the effect can generalize to unstudied items as well as other cognitive abilities.