Home-Based tDCS for Schizophrenia: Exploring the Feasibility of a Standard Operating Procedure

1. Introduction

Transcranial direct current stimulation (tDCS) is a promising non-invasive brain stimulation (NIBS) technique for persistent auditory verbal hallucinations (AVH) in schizophrenia (Cheng et al., 2020; Fregni et al., 2021; Sreeraj et al., 2018). It is a safe and easy to administer. Compared to other NIBS techniques like transcranial magnetic stimulation, its affordable pricing increases its possible utility in resource-limited settings and developing countries. The clinical effects last for short durations, necessitating frequent hospital visits for more sessions posing logistic and sustainability challenges. To address these, the concept of at-home or domiciliary tDCS has emerged, involving self-administration or administration by trained caregivers, ideally under remote supervision of the experts (Charvet et al., 2020). Domiciliary tDCS offers frequent continued sessions or maintenance or booster sessions. While studied in depression and other disorders, reports of its applicability in schizophrenia have been limited, with only three case reports available (Andrade, 2013; Desousa, 2017; Schwippel et al., 2017). These reports indicate varying durations of tDCS application (3 months - 3 years) with transient (Schwippel et al., 2017) or sustained (Andrade, 2013; Desousa, 2017) improvement in AVH in treatment-resistant schizophrenia (TRS).

However, administering home-based tDCS presents unique challenges, like determining the accurate placement of electrodes, delivering exact stimulation parameters, training the caregivers, remote monitoring of the stimulation sessions by the mental health professionals, maintaining and handling the stimulation device, assessing and managing adverse-effects, and preventing misuse, such as using the device beyond its intended clinical recommendations. In this case report, we describe the application of domiciliary tDCS in a patient with TRS. This report highlights the feasibility of domiciliary tDCS and the developed procedure for ensuring its safe and effective application.

2. Methods

2.1. Case Description

A 19-year-old male presented with an illness of 3 years duration characterised by schizophrenia symptoms - 2nd person AVH, the delusion of persecution, love, and control, poor self-care, disinhibited behaviour, social withdrawal, and amotivation causing significant dysfunction. He had a poor response to adequate trials of risperidone (8mg/day) and amisulpride (600mg/day). Due to treatment resistance, clozapine was initiated and titrated to 200mg/day alongside amisulpride at 200mg/day. Mild improvement was observed with clozapine and amisulpride, but distressing AVH with acting-out behavior persisted. The score on the Auditory Hallucination Rating Scale (AHRS) was 27, the Psychotic Symptoms Rating Scale-Auditory Hallucination Subscale (PSYRATS-AH) score was 34, the Scale for Assessment of Positive Symptoms (SAPS) was 44 and Clinical Global Impression – Severity (CGI-S) score of 5. To address this, tDCS augmentation was proposed, left fronto-temporoparietal montage: anode over left dorsolateral prefrontal cortex (F3), and cathode over the left temporoparietal junction (midpoint between T3 and P3) (Bose et al., 2019). Conventional tDCS was administered at 2mA for five days, twice daily, with a 20-minute intersession interval using an indigenously developed standard device (WISER tES, https://circuitects.com/portfolio/wiser-tes/). Following a reduction in the severity of AVH (AHRS =22, PSYRATS-AH =27, SAPS = 35, CGI-S =4), tDCS was continued for another five days, with plans for home-based administration. A standard operation procedure was implemented to train the patient’s caregivers in administering tDCS.

2.2. Standard Operational procedure

The training was implemented during the additional five days of hospital-based administration. To ensure the safe administration of domiciliary tDCS, the following factors were considered based on previous recommendations (Charvet et al., 2020).

1. Device-related factors: The home-based tDCS was offered using an indigenously developed device that met medical safety standards. The device had built-in features that made it a suitable choice for home-based administration.

   • It is portable, hand-held, programmable, and user-friendly.

   • It is battery-operated using rechargeable batteries and safety-certified for International Electrotechnical Commission standards.

   • It has multiple safety features, like non-conductive external material and a touch-protected stereo jack for connecting electrodes.

   • The option of simultaneous stimulation and charging of the battery is disabled.

   • The stimulation is administered only if the contact quality between the scalp and the electrodes is adequate (impedance<10kOhms and/or voltage<24V) with a maximum output of 2mA current.

   • It features a graphical user interface with a digital display of parameters like time lapsed, current intensity, impedance, and a battery gauge for real-time monitoring.

   • It has an abort button to stop the stimulation session anytime for emergencies or if the patient has any immediate concerns.

   • Flexible options to adjust ramp-up and ramp-down duration are available.

   • The device logs each session with impedance data captured at a 1Hz sampling rate with the timestamps for post-session verification.

   • Stimulation parameters can be preset and locked so that they cannot be inadvertently altered by the patients/caregivers during home-based sessions.

2. Patient and caregiver-related factors: The suitability of domiciliary tDCS was decided based on certain conditions regarding the patient and the caregiver pair.

   • Tolerability and effectiveness of the tDCS protocol were ensured with multi-session tDCS before home-based sessions were advised.

   • A need for continued tDCS treatment was ascertained because of the persistence of targeted symptoms.

   • No clinical emergency was anticipated - no agitation/aggression, adequate self-care, and could make informed treatment decisions.

   • The caregivers understood the need for the tDCS application and the technical processes.

   • They were found to have the technical know-how to handle medical-grade equipment and were trainable for device maintenance, initiation, and termination of stimulation sessions.

After ascertaining patient and caregivers’ suitability, they were trained for domiciliary administration, following these steps:

Training for home-based tDCS:

Observational learning:

• Initial tDCS sessions were provided by expert tDCS administrators at the hospital for at least 5-10 sessions to familiarize the patient and the caregivers with the stimulation process and monitor any adverse effects using a structured scale (Brunoni et al., 2011; Chhabra et al., 2020). The caregivers attended these sessions.

• Additionally, an educational video developed by the team describing the steps of tDCS stimulation was shown.

Training on Mannequin:

• Electrode placement: The caregiver was trained to locate the precise scalp locations on a mannequin head model.

• Setting up tDCS: They were trained to use the appropriate amount of saline to soak the sponges, place the electrodes, tie and untie them with rubber bands at the correct scalp locations, and maintain the stability of the set-up while ensuring the comfort of the patient.

• Operating the device: They were also trained to operate it, connect the cables, and initiate and terminate the sessions.

Assisting in live-patient sessions:

• Next, a few hospital-based tDCS sessions for the patient were assisted by caregivers and trainers/expert administrators.

• The training was provided to caregivers to monitor the adverse effects and mitigate discomfort or unintended situations like montage set-up displacement or stimulation interruption.

• Training on post-session care of the device, like recharging the device, cleaning electrodes and sponges, and storing the device and accessories safely, was also provided.

Assessment of the caregiver’s competency and implementation of the treatment plan:

• The competency of the caregivers was assessed during successive five training days on a Likert scale ranging from 1 to 5 (1 - Worst and 5 - Excellent) on five different domains: electrode preparation and placement, device setting-up and initiating stimulation, monitoring stimulation, post-stimulation assessment, and device maintenance on the first day and the fifth day of tDCS administration. To ensure competency, a fixed criteria of score ≥ 4 on all domains was defined. Both caregivers had an average score of 3 on the initial day, but it improved to above 4 (Good) (Table 1) on all administration steps by the fifth day.

• Once the trainers/doctors were confident about the feasibility of home-based tDCS, the device and all the other accessories were handed to the caregivers.

• The device was preset with required stimulation parameters, thus restricting caregivers from adjusting any stimulation settings.

Remote supervision:

• For the initial three days of home-based sessions, the caregivers conducted the sessions with video-call-based remote monitoring by the trainers/doctors through video calls.

• Following this, caregivers independently administered the sessions without additional assistance/supervision from the trainers/doctors.

• Sessions were scheduled for administration during working hours to ensure immediate availability of remote support if any need arose.

Domiciliary treatment was continued for ten days, maintaining the same parameters used in the hospital-based administration. After completing the 10-day domiciliary treatment, the patient was noted to sustain the improvement from the initial hospital-based tDCS treatment (AHRS=22 and AHS-PSYRATS=27, SAPS = 35, CGI-S =4), with no side effects reported as assessed using a structured questionnaire (Chhabra et al., 2020).

3. Conclusion

tDCS is a scalable therapeutic NIBS modality due to its simplicity, safety, and cost-effectiveness. Nevertheless, proper procedures must be followed to avoid tDCS being inefficacious and leading to adverse events. This necessitates the need for adequate training of the individuals who would assist patients in receiving personalised tDCS sessions. The current manuscript documents the procedure followed in training, monitoring, and administering domiciliary tDCS, exemplifying this case report. Several incremental steps like training videos, training for electrode placement and set-up on the mannequin head, in-person supervision with required hand-holding, and remote monitoring were included to train the caregivers to ascertain safety and prevent device misuse. Notably, the administrators lacked medical backgrounds, which differed from the previous case report (Andrade, 2013). The patient reported no adverse effects, and the caregivers could administer the sessions at home with relative ease. This case report supports the feasibility and scalability of home-based tDCS by training caregivers, minimizing hospital visits, and easing the logistical and economic challenges.

Figure 1a. Competency Assessment of Caregivers Before and after receiving training for home-based tDCS administration.

Competency Likert Scale Scoring: 5: Excellent. Competency comparable to an expert; 4: Good. All the steps were followed. Minor corrections are needed. However, it will not interfere with tDCS efficacy; 3: Okay. Some steps were inappropriate and could possibly influence the tDCS’s efficacy; 2: Poor. The caregiver has made gross mistakes that would influence the efficacy of tDCS; 1: Worst. The caregiver abandons the administration midway or, does not attempt the administration of tDCS, or makes any gross errors that could be potentially harmful to the patient or the device.

Figure 1b. Change in psychopathology post-10 days of intervention at the hospital followed by post 10 days of home-based tDCS.

AHRS- Auditory Hallucination Rating Scale, PSYRATS-AH - Psychotic Symptoms Rating Scale-Auditory Hallucination Subscale, SAPS - Scale for Assessment of Positive Symptoms