This manuscript provides an updated remote supervision protocol that enables participation in transcranial direct current stimulation (tDCS) clinical trials while receiving treatment sessions from home. The protocol has been successfully piloted in both patients with multiple sclerosis and Parkinson's disease.
The remotely supervised tDCS (RS-tDCS) protocol enables participation from home through guided and monitored self-administration of tDCS treatment while maintaining clinical standards. The current consensus regarding the efficacy of tDCS is that multiple treatment sessions are needed to observe targeted behavioral reductions in symptom burden. However, the requirement for patients to travel to clinic daily for stimulation sessions presents a major obstacle for potential participants, due to work or family obligations or limited ability to travel. This study presents a protocol that directly overcomes these obstacles by eliminating the need to travel to clinic for daily sessions.
This is an updated protocol for remotely supervised self-administration of tDCS for daily treatment sessions paired with a program of computer-based cognitive training for use in clinical trials. Participants only need to attend clinic twice, for a baseline and study-end visit. At baseline, participants are trained and provided with a study stimulation device, and a small laptop computer. Participants then complete the remainder of their stimulation sessions at home while they are monitored via videoconferencing software.
Participants complete computerized cognitive remediation during stimulation sessions, which may serve a therapeutic role or as a "placeholder" for other computer-based activity. Computers are enabled for real-time monitoring and remote control by study staff.
Outcome measures that assess feasibility and tolerance are administered remotely with the aid of visual analogue scales that are presented onscreen. Following completion of all RS-tDCS sessions, participants return to clinic for a study end visit in which all study equipment is returned.
Results support the safety, feasibility, and scalability of the RS-tDCS protocol for use in clinical trials. Across 46 patients, 748 RS-tDCS sessions have been completed. This protocol serves as a model for use in future clinical trials involving tDCS.
Transcranial direct current stimulation (tDCS) is a type of noninvasive brain stimulation with a wide range of potential therapeutic uses. A mild electrical current (typically ≤2.5 mA) is directed through electrodes placed on the scalp to influence brain activity by altering neuronal polarization1. tDCS is typically paired with a rehabilitation strategy in efforts to increase training outcomes. Other popular forms of neuromodulation, such as repetitive transcranial magnetic stimulation, are used to similar ends, but lack key advantages of tDCS such as its portability, simple applicability, and relative inexpensiveness1,2.
Multiple tDCS sessions are required for cumulative clinical benefit1,3. Behavioral effects, such as reductions in fatigue or depressive symptoms, rely upon repeated, consecutive sessions. For instance, studies have only observed such treatment effects after twenty or more sessions4,5.
Typically, tDCS is administered in clinic by a trained clinician or study personnel familiar with the facets and operations of the device and stimulation method. This is costly to both the patient and clinician as significant time, clinic space, and travel are required. As a solution to the need for daily, in-clinic tDCS, we have developed remotely supervised tDCS (RS-tDCS)6. This protocol enables at-home tDCS sessions to be completed through controlled supervision and guidance as provided by study personnel via a study laptop and has the benefit of only requiring two in-clinic visits (baseline and study-end visits) by the participant.
The patient populations chosen to pilot the methodology of this protocol include patients with multiple sclerosis (MS) and Parkinson's disease (PD). Both diseases impose distinct deficits on the patient, such as symptoms of fatigue in patients with MS and dyskinesia in patients with PD. tDCS presents a unique opportunity to improve symptoms of fatigue7 and cognitive dysfunction8,9,10 as well as to promote motor learning and control11,12. Participants representing a spectrum of disease severity were included in this study with steps taken, as permitted by RS-tDCS, to accommodate their respective disability.
Among these populations, people with MS or PD may have distinct obstacles that prevent them from conveniently reaching the clinic. Motor impairments such as confinement to a wheelchair or cognitive deficits that result in loss of autonomy can limit their inclusion in clinical trials or other cognitive studies. Additionally, familial and professional obligations reduce the time available to attend clinic, limiting availability for cognitive remediation trials confined to the clinic13. These patient populations, due to their diverse range of impairment, serve as model populations to test the limits and feasibility of RS-tDCS.
The RS-tDCS protocol marks a major step in the tDCS field, since it studies the use of stimulation, as it will be administered in a patient's care at home. The protocol strengthens the rate of recruitment, trial completion rate, relieves patient burden, and minimizes clinical costs. Herein we report the specific details of the protocol as well as preliminary findings regarding the feasibility, safety, and tolerability of the device when remotely administered.
All procedures and device protocols have been approved for human subjects by institutional review boards at both Stony Brook University and New York University Langone Medical Center.
1. Participant Recruitment and Screening
2. Baseline Study Visit
Figure 1: Left anodal DLPFC montage used in both studies. The red and blue patches are modeled representations of the left anode and right cathode, respectively, placed upon a scalp. Please click here to view a larger version of this figure.
3. At-home tDCS Sessions
4. Post-stimulation Visit
5. One Month Follow-up Survey
One pilot study has been completed using the RS-tDCS protocol at Stony Brook University and a second is currently ongoing at NYULMC. Respective institutional review boards approved all study procedures at both sites.
Since the presented studies were both intended to pilot the RS-tDCS methodology, participants were not selected on the basis on symptoms but instead using broad eligibility criteria for both patients with MS and PD. Similarly, patients who could not tolerate the target amperage of the stimulation were given an option of lower amperage (detailed further below).
Study 1:
MS participants were recruited through the Lourie Center for Pediatric MS at Stony Brook between the dates of March 2015 and February 2016. This trial was an open-label RS-tDCS study to pilot the feasibility of the protocol in MS. All participants knowingly received 20 minutes x 1.5 mA (or 1.0 mA if 1.5 mA was not initially tolerated) open-label tDCS applied to the DLPFC (left anodal)23,24,25,26,27. During the stimulation, cognitive training games30 targeting attention, information speed, and working memory were completed. The first session was completed at the end of the baseline visit in clinic and the remaining sessions were completed at-home, daily, five days per week (M-F) over the course of two weeks, for a total of nine sessions at home. In total, 26 participants were recruited for this study.
Study 2:
MS Arm – Participants with MS were recruited through the NYULMC's MS Comprehensive Care Center between the dates of January 2016 and October 2016. This arm of the study was a randomized, double-blinded, sham-controlled trial using 2.0 mA (or 1.5 mA if 2.0 mA was not initially tolerated) of RS-tDCS applied to the DLPFC (left anodal) for twenty minutes daily. The first stimulation session was completed at the end of the baseline visit in clinic while the remaining nineteen at-home sessions were completed over the following four weeks (M-F). This study is ongoing and we report the findings of 20 MS participants that have been recruited and completed the study.
PD Arm – Participants with PD were recruited through the NYULMC's Fresco Institute for Parkinson's and Movement Disorders between the dates of June 2016 and December 2016. This arm's focus was to pilot the RS-tDCS protocol in patients with PD, similar to the pilot study conducted with MS. The study was open-label, and all participants knowingly received 2.0 or 1.5 milliamps of tDCS applied to the DLPFC (left anodal). Similar to Study 1, the first session was completed at the end of the baseline clinic visit and the remaining nine sessions were completed at the participant's home remotely (M-F). This study is ongoing and we report the completed findings from 6 PD participants that have been recruited.
To assess the feasibility and tolerability of the RS-tDCS protocol, we measured the percentage of completed sessions, adverse event rates, and the average intensity of the most common adverse events.
A total of 748 RS-tDCS sessions have been successfully completed across 46 participants in approximately a year. This supports the feasibility of the RS-tDCS protocol. In Study 1, 2 participants discontinued tDCS: one participant discontinued due to personal obligations and the other participant discontinued due to study stop criteria of uncomfortable sensations of skin burning greater than a score of 7 (albeit without physical burns). In Study 2, 2 participants were discontinued: one was discontinued due to an abnormal adverse event of "tongue tingling" and the other was discontinued due to a pain rating of 7 (on the 1-10 analog scale) from headaches. From the PD cohort, no patients have been discontinued. In total, 4 patients were discontinued from the study and none of them were discontinued due to an inability to complete the RS-tDCS sessions.
The numbers of adverse events per stimulation type were tallied and their rates of occurrence were calculated. The stimulation types have been placed into four different categories: 1.5 mA open-label, 2.0 mA blinded, 2.0 mA open-label, and the sham condition. The rationale for division into these categories is that participants may have differing interpretations of their sensations depending on what they expected during stimulation. As seen in Figure 1, the three most common adverse events were sensations of skin tingling, itching, and burning (no participants received physical burns).
Figure 2: Rates of adverse events experienced with tDCS. 1.5 mA OL refers to sessions in which participants knowingly received 1.5 mA of open-label tDCS. 2.0 mA BL refers to sessions in which participants were blinded to the stimulation they were receiving which was 2.0 mA tDCS. 2.0 mA OL refers to sessions in which participants knowingly received 2.0 mA of open-label tDCS. Sham refers to sessions in which participants were blinded to the stimulation they were receiving but only received 60 s of stimulation at the beginning and end of the 20 min session in order to simulate active tDCS. Please click here to view a larger version of this figure.
The average intensity of the most common adverse events has been calculated. As shown in Table 1, the average intensity of the most common adverse events did not exceed a score of 3 (on a 1-10 visual analog scale, 1 being mild and 10 being extreme) for any of the adverse events in any of the stimulation conditions.
Session Condition | Total Sessions | Tingling (SD, n) | Itching (SD, n) | Burning Sens. (SD, n) |
2.0 mA Blinded | 201 | 1.6 (0.8, 75) | 2.2 (0.9, 36) | 2.5 (1.3, 59) |
2.0 mA Open-Label | 104 | 1.9 (1.2, 43) | 1.8 (1.1, 8) | 2.0 (1.4, 32) |
1.5 mA Open-Label | 268 | 2.4 (2.2, 161) | 2.0 (1.6, 65) | 2.9 (2.0, 79) |
Sham | 175 | 1.9 (1.2, 72) | 1.7 (0.9, 17) | 1.6 (1.2, 46) |
Table 1: Average intensity of commonly experienced adverse events on a visual analog scale (1-10, mild-intense).
The stimulation also shows promise for symptom management as can be seen in Figure 3. Cohen's d values were calculated for change in mood, fatigue, and pain from baseline to study end for MS patients in studies 1 and 2. PD patients were not included in this analysis due to the small cohort completed to date (n=6). An effect size analysis was employed due to the small sample sizes in each study to identify signals suggesting efficacy. The active sessions in Studies 1 and 2 showed far greater average effect sizes for improvement. On average, participants who received active tDCS reported greater positive effects, and had less negative effects, fatigue, and pain by study end compared to the sham tDCS group.
Figure 3: Cohen's d for symptomatic outcome measures. Positive effects were shown by the participants receiving 20 active sessions of rtDCS while the participants in sham group had negligible effects. Please click here to view a larger version of this figure.
This study employed the DLPFC left anodal montage24, but this could easily be interchanged for another montage and the effects of stimulation may change accordingly. Depending on the location of stimulation, the brain effects and side effects experienced may change1. Stimulation type, such as intended inhibition instead of excitement may influence effects as well. Similarly, the form of remediation paired with stimulation may influence the results of the study31. Future experiments need to be conducted with different remediation strategies paired with RS-tDCS to identify its specific affects.
While the RS-tDCS protocol focuses on providing tDCS to patients in their homes, there may still be a place for stimulation provided in a clinical setting. For example, more complex montages, such as those used by HD-tDCS, may not be feasible at home even with proper training32. The RS-tDCS protocol provides a detailed procedure to ensure clinical trial standards of treatment sessions and dosing control while delivering the stimulation at home using a tele-rehabilitation protocol. Uniform electrode preparation and placement as well as simplified procedures, including the incorporation of simpler sponge electrode techniques, ensure consistency across participants. The RS-tDCS protocol allows for the completion of stimulation sessions by cognitively and physically impaired individuals who otherwise would have great difficulty reaching the clinic daily.
All troubleshooting can be immediately addressed by the study personnel who are live video-conferencing with participants during at-home stimulation sessions. In the case that the study laptop is malfunctioning, a simple restart of the computer can resolve technical issues. In the case that study equipment malfunctions from a laptop or the tDCS device are not resolved following technical support, then study personnel should arrange for the delivery of new, properly functioning equipment.
The protocol is inherently reliant upon internet access, which is the method's greatest limitation. Currently, those without internet cannot be enrolled in any trial using RS-tDCS. The internet utilized in conjunction with our protocol enables the remote supervision in our RS-tDCS protocol.
RS-tDCS remains one of the few recognized and feasible protocols for at-home delivery of tDCS33. The large volume of sessions completed with the protocol (748 in little over a year), speaks to the effectiveness of the protocol, as other centers have reported smaller and underpowered studies. The RS-tDCS protocol has been effective in providing tDCS directly to patients with a wide range of disabilities. By enabling clinical trials with the RS-tDCS protocol, rapid recruitment and swift trial completion are possible.
The RS-tDCS protocol is generalizable to other neurologic conditions. As demonstrated here, we have already generalized our protocol to PD and plan to demonstrate the applicability of the protocol to other conditions. Both the parameters of stimulation and the remediation strategy can be adjusted to target specific treatment outcomes.
The authors have nothing to disclose.
The authors would like to thank collaborators at City College of New York and Soterix Medical for their assistance and support.
tDCS Mini-CT device | Soterix | Provides direct current stimulation | |
EASYstrap with conducting cables | Soterix | Sponges attach to the strap and the strap lays on the head | |
EASYpad sponges | Soterix | Premoistened sponges with 5mL of saline. Snaps into electodes. | |
Stream laptop | Hewlett Packard | Used for videoconferencing and cognitive remediation. | |
Device Charger | Soterix | Recharges the Mini-CT. | |
TeamViewer Software | Teamviewer | Remote desktop software that enable remote control of participant's computers. | |
Vsee Software | VSee Lab, Inc. | Enables HIPAA compliant video-conferencing | |
Lumosity | Lumos Labs | Online platform used for cognitive remediation |