Acceptability of transcranial direct current stimulation in children and adolescents with ADHD: The point of view of parents

Abstract

Transcranial direct current stimulation (tDCS) is a novel treatment option for attention deficit hyperactivity disorder. To facilitate translation into clinical practice, we interviewed parents of children who have experienced experimental tDCS. A grounded theory approach using open, axial, and selective coding provided seven emergent themes for acceptability: tDCS provides hope for parents, safety tolerability and side effects of tDCS versus medication, burden of treatment, education and trust with care providers, cost and coverage, unestablished tDCS efficacy versus established medication effectiveness, perceived compliance of tDCS versus medication. Results suggest tDCS is acceptable but depends on evidence of effectiveness and regular availability.

Keywords

attention deficit hyperactivity disorder non-invasive brain stimulation pediatric neuropsychiatry patient perspectives and acceptability transcranial direct current stimulation

Introduction

Attention deficit hyperactivity disorder (ADHD) is the most common neurodevelopmental condition and there remains to be any intensive long lasting treatment options. Current treatment methods are generally limited to long term commitments to pharmaceuticals, neurofeedback (NFB), and behavioral or psychosocial therapies which are not always effective or manageable for the parents and children. Transcranial direct current stimulation (tDCS) is a novel potential treatment option for children with ADHD (Breitling et al., 2016; Cosmo et al., 2015; Soff et al., 2017; Sotnikova et al., 2014) and other neuropsychiatric conditions (Lee et al., 2019; Rivera-Urbina et al., 2017) that may be more manageable than medication. tDCS is a non-invasive neuromodulation technique that utilizes low amplitude direct currents applied via scalp electrodes to modulate the level of excitability in specific brain regions (Giordano et al., 2017). While tDCS has mostly been used experimentally in the laboratory and in clinical trials it is in the process of becoming a standardized clinical tool (Giordano et al., 2017; Lefaucheur et al., 2017). There are several stages involved in this process such as establishing safety and tolerability, efficacy and effectiveness, and lastly translation and dissemination (Steele et al., 2008). The present article will focus on the final stage of this process, translation and dissemination.

Several reviews have been conducted to understand and compare the acceptability of pharmaceuticals with behavioral/psychosocial (Bennett et al., 1996; Johnston et al., 2008; Stuhec et al., 2015), with NFB (Catalá-López et al., 2017; Yan et al., 2019), and with other interventions for ADHD. In each of these studies the non-pharmacological approaches were found to be more acceptable despite often being less effective. In the studies by Demidovich (Demidovich et al., 2011) and Johnston (Johnston et al., 2010) it is also shown that acceptability can be a useful predictor for the likelihood of starting and continuing an ADHD treatment (Krain et al., 2005). Given the novelty of tDCS, studies evaluating its acceptability are scarce, and more so still in the context of ADHD. A major tDCS review from Bikson (Bikson et al., 2016) noted that tDCS is safe and tolerable in adults and so far appears to be in children; however only 5% of published research has been conducted in children. Current tDCS literature is further limited through a narrow definition of acceptability, using only quantitative questionnaires or measuring rate of drop outs as a proxy (Aparicio et al., 2016). Studies rarely investigate the acceptability of tDCS beyond the narrowly operationalized “rate of drop outs,” let alone in pediatrics or ADHD. Although tDCS has proven to be very acceptable as defined by rate of drop outs (Aparicio et al., 2016; Bikson et al., 2016), there are several other nuances that must be considered to truly understand the acceptability of this specific intervention in a neuropsychiatric setting.

Sekhon, Cartwright, and Francis (Sekhon et al., 2017) meta-reviewed 43 reviews which measured acceptability of healthcare interventions. They found that 23 of these studies defined acceptability by rate of drop outs, where several other studies defined acceptability via cognition/perceptions, affect, or a combination of these. To better understand healthcare interventions, they developed the Theoretical Framework of Acceptability (TFA) which posits seven component constructs and the following definition: “Acceptability is a multi-faceted construct that reflects the extent to which people delivering or receiving a healthcare intervention consider it to be appropriate, based on anticipated or experienced cognitive and emotional responses to the intervention” (Sekhon et al., 2017: 8).

Acceptability focuses on one intervention, but preference requires an explicit comparison to another option. Preference between treatment options (between medications, or medication versus psychosocial treatments) have been studied with parents. They consistently showed that treatment outcome is the most salient attribute for choice (Schatz et al., 2015). Preference toward medication decreased for children of younger age and with milder symptoms (Waschbusch et al., 2011) but increased with time elapsed since diagnosis (DosReis et al., 2017). None of these studies considered tDCS or other brain stimulation approaches.

The current study

The objective of this research is to gain a deeper understanding of families’ experiences of tDCS use in their child and if it is acceptable compared to medication. Given the subjective nature of each family’s experience it is advantageous to utilize a qualitative inductive research approach (Glaser and Strauss, 1967; Taylor, 2013). Such an approach does not attempt to verify a specific construct or hypothesis per se, but instead aides in developing a deep understanding of the perceptions of participants through far-reaching analyses of their experiences. Using an inspired Grounded Theory (Taylor, 2013) approach we have obtained an integrative collection and analysis of parents’ experiences and perceptions regarding tDCS use in their children.

Grounded Theory approaches the research process from an inductive position, with the ultimate goal of generating a theory based on themes that emerge from data collection: In this case, a theory of what makes tDCS acceptable. It allows the participants to describe their experiences in a profound way that is meaningful and comprehensive to them. It positions participants as the experts of their experiences allowing them to create their own narratives about tDCS. In this perspective, Grounded Theory will allow us to reach the specific objectives of this study.

Methods

Participant sampling and recruitment

Participants from this acceptability study represent about half of the children from a larger sample of a separate study conducted by our group which investigated tDCS safety and tolerability in children and adolescents (Buchanan et al., 2019). Parents who enrolled one or more of their children in the safety study were subsequently asked if they would be willing to participate in our acceptability study. In the interest of emphasizing tDCS acceptability in children with ADHD, criterion based sampling was used (Lecompte and Goetz, 1982; Thé Riault and Gazzola, 2005). This included the youngest children with ADHD; though the final sample did include a parent of two healthy controls.

Participant demographic data

Eight parents were recruited; representing a sample of 14 of their children (five females) aged 6 to 14 (mean 9.21, SD 2.72). During the initial tDCS safety study the children participated in to two ten minute sessions of tDCS with randomized electrode locations and randomized/double blinded amplitude (0-2mA). The mean amperage across these 28 sessions was 1.1mA. Quantitative safety and tolerability measures were taken and at least one parent was present throughout the entire study. The qualitative interviews were conducted on the parent who was present with their child during the initial safety study. Incidentally, the parental participants were all mothers. Joint Research Ethics was obtained from the Children’s Hospital of Eastern Ontario (CHEO) and Carleton University.

Data collection

Qualitative semi-structured interviews (60–90 minutes) were conducted by the first author through a teleconferencing system enabled for digital recording. The recording was subsequently manually transcribed verbatim by a member of the research team. There was a total of 165 pages of text and 60698 words (12 pt Times New Roman, single space). Interviews were additionally evaluated using concurrent data analysis and collection, which allowed for initial interviews to inform subsequent themes. The researcher’s interview questions and demographic questionnaire are available in the supplementary materials. Demographic data was collected but not reported given the omission of identifiers.

Data analysis

Coding followed the grounded theory procedure (Taylor, 2013) and was completed twice by two separate researchers. The goal was to identify emerging themes utilizing: open, axial, and selective coding. Data was first assessed using line-by-line open coding, in which significant units of text containing salient themes were labeled using descriptive codes. These are descriptive words or ideas which participants consistently used to convey their experiences and opinions. Next, these codes were synthesized into categories based on the units’ common properties. The process of axial coding was then initiated, whereby the relationships between the categories were determined through the researcher’s interpretive lens. Finally, selective coding of the data was engaged, whereby the categories and their relationships were interpreted to describe newly emerging themes regarding the use of tDCS in children and adolescents. Data analysis was completed using the NVivo qualitative software package (version 12).

Results

Several themes emerged from the analysis of the interviews. These include: tDCS as a source of hope for parents, safety tolerability and side effects of tDCS versus medication, burden of treatment, education and trust with care providers, cost and coverage, unestablished tDCS efficacy versus established medication effectiveness, perceived compliance of tDCS versus medication. The following sections describe these themes in detail and substantiate them through illustrative quotes from participants.

tDCS as a source of hope for parents

Parents agreeing to enroll their children in a study regarding a potential novel medical treatment presumably do so in the hope that said treatment may at one point benefit their child. Herein parents have weighed the potential benefits of tDCS treatment against perceived cons. This theme was found in all transcripts:

“Certainly my motivation right away was yes I want to participate in this study because I just felt right off the bat that this is something that my child could benefit from. . .I felt that it’s important for us as a family, so my family and I, to do whatever we need to do right now to help advance any form of science that would help our child.”

The perceived benefit to children at large also appeared to be equally important to parents as families hope for tDCS to become more accessible through regulatory agencies such as FDA and Health Canada: “It’s my hope that it [tDCS] can be used in children and that we can see this happening in Canada sooner than later *laugh* and certainly I think without a doubt in adults, but I think certainly my hope is for children.” Another parent notes the same: “Honestly I’m hoping we could get it actually passed [by a regulatory agency], so these kids could have this done rather than have to take the medication.” One participant rationalized their hope: “I think the nice thing about the short and effective duration is that there is that hope of a light at the end of the tunnel.” Another participant similarly noted, “I think there are a lot of parents who are hopeless right now that would jump on that idea.”

In each of these cases the parents express their feelings and motivations to find a better treatment for their child and they hope that tDCS can be the answer. Participants further expressed that tDCS may also benefit and be accepted by other families with similar circumstances.

Safety tolerability and side effects of tDCS versus medication

It became clear that most parents experienced conflicting decisions regarding their child’s use of medication, and were more acceptable towards their choice to pursue tDCS. For instance, one participant notes: “it’s safer than having all these pills around because these days with kids, with everybody talking about overdosing and all that, then there would be no pills in the house, it would be safer.” Another parent felt the same way: “Putting medication into your body which is equivalent to ‘speed’ is not something that parents like to do for their children; I mean these medications are addictive. If they are used wrongly on the streets they could be very dangerous so I can’t imagine tDCS would have something worse than that.”

From a more general point of view one parent pragmatically notes: “He’s been on probably 4 or 5 different meds his whole life until we finally found the right one and certainly side effects of his meds are way worse.” For another family, the medication actually does work well: “I already know that the medication helps. . .but I don’t like the side effects and the fact that it’s a Band-Aid and the days that he takes it he’s good and the days he doesn’t he’s not.” The same parent further expresses this through her discourse on not using medication at all: “He’s had some pretty serious side effects from medications and you know we’ve tried the whole route of no medication as well because most parents want to do that before they put the child on medication.”

On the other hand, participants appeared to feel quite good about tDCS safety and tolerability: “Based on all my children’s experiences and my own I would rate [the safety] 10 out of 10. . .the procedure itself was very safe.” In the same vein, another participant concurred by saying: “Well it seems pretty safe to me, like for me I would rate it a 10. I’d rather see him being on the stimulation [than on pharmaceuticals].” Finally, one parent summed up her feelings when she said “my children have had worse experiences at the dentist!”

Participants displayed a level of discomfort with various safety issues surrounding medication use and they see tDCS as a potential solution to this. Overall, it seems that the parent’s preference to avoid side effects and maintain a lasting behavioral change motivates them toward tDCS despite the effectiveness of the medication.

Burden of treatment

Participants viewed medication as a burden due to its daily and long term use, side effects, and the occasional hassle of filling prescriptions. All of this despite it being effective in most cases:

“He’s actually responding very well to medication but. . .you know, he’s on six pills a day *laugh*. . .I’m still not quite there on the idea of fully embracing the fact that my child is going to be on medication his whole life, so yes if there was an alternative placed in front of me I would take the alternatives hands down.”

In contrast with medication, the potential perceived burden for tDCS was more concerned with the practicality of regularly attending the clinic. For example: “I mean it’s definitely a lot especially for us because we live 25 to 30 minutes away. . .but I mean we do the things we have to do.” From the point of view of participants, like medication, tDCS would also be more acceptable if it were available at home or remotely.

“My concern as a parent also would be, is this something that you always have to [travel] to in order to do it, or something that I can have this machine in my house and just switch it on for this time frame? Because that’s another thing is the cost of transportation to get there, time off from work, or the convenience of it all.”

Participants anticipate that the intense short duration of a tDCS treatment may be challenging but the same is expressed regarding years of medication use. Overall, parents perceive the accessibility of tDCS as a burden particularly compared to medication which is generally accessible at home and school.

Education and trust with care providers

It was important for families’ comfort and acceptability of tDCS that they were educated on what to expect during the tDCS sessions.

“Once we sat down and we talked before we did the whole stimulation, you had explained everything perfect. The more information we had, it just cleared up the worry of what would have happened. I thought there was a lot more to be hooked up on his head. But seeing what was actually was hooked up was a big difference than what I had originally thought. I was like wow okay this is going to be easy.”

It appears that the accurate provision of information attenuates potential concerns. Some participants sought to do this on their own as well: “So I looked at the pamphlet and read through and looked for information online which helped me with my decision to participate. . .I got from the pamphlet that it was definitely nothing like electroshock [therapy].” But some participants were put off by the name and idea of electrical stimulation:

“It doesn’t sound inviting I can tell you that *laugh* like if you just went up to somebody and, like the words cranial and stimulation to me makes me think of wires in someone’s brain, internally. . .It’s a little bit of a daunting terminology but I mean most medical terms are anyway.”

According to participants, another major determinant of whether or not to allow their child to use tDCS was: the trust and credibility of their healthcare providers, the organizing bodies associated with the study, and the researchers administering the intervention. In one case: “I was approached at my practitioner, my kid’s doctor who has been seeing my kids for some time. . .Basically I put my trust in the organization which is a children’s organization that I felt really comfortable that they will not put my kids in harm.” Finally, trust with regards to the researchers administering the tDCS intervention was displayed by several participants: “I felt I trusted you and there was no way you would do this thing if you felt like it would hurt my kid.”

Analyses demonstrate that for participants there is an absolute importance of establishing a rapport of trust with the provider. This trust is instilled by the reputation of the provider and the clear transmission of information to the participant.

Cost and coverage

For participants, cost and coverage appears to be an important concern. “Cost always of course plays a factor. So if it was a covered cost and more effective, then it would be a no brainer to go and have [tDCS] done because it would be a lot less of the side effect.” Another participant added, “Obviously money is a huge thing as well, I mean if I was looking at all my options and I had insurance coverage and everything was out on the table for me, then for sure [tDCS].” This participant also weighed the effectiveness with the cost: “Even if tDCS worked a little bit slower but didn’t have all those nasty side effects of a pharmaceutical and even if it cost a little bit more, if I was able to do that then I would be inclined to do that.” Finally, another expressed the same: “It would have to be a pretty significant cost for me to say no, especially if it were more beneficial than the medication.”

It appears that parents desire the benefits of tDCS treatment but that insurance / coverage of the treatment is important to their choice treatment modality and tDCS acceptability. The effectiveness however seems to play a more important role that could trump the burden of cost.

Unestablished tDCS efficacy versus established medication effectiveness

The effectiveness of tDCS as a treatment in comparison to their child’s current treatments was of particular interest to parents. “If there was proof of effectiveness that was comparable to medication, then that would be what would influence my decision [to choose tDCS over medication].” Interestingly parents for whom medication is ineffective and effective both share preference for tDCS if it is established as effective. In the case of a child who responds poorly to medication: “So we know with my child that pharmaceuticals have a lot of problems so if I could say that it was more effective to do the tDCS it would be no question I would do that immediately.” Another participant elucidates this, indicating that even if the tDCS intervention proved to be somewhat less effective than pharmaceuticals, they would still opt for the non-drug route: “If you compare to medication for instance, if I put the medication at 100% effective for example and I put the tDCS at 50% maybe I’ll say it’s not good enough. But if it’s at 75% or 80% as good as the medication with much less side effects then I’ll stay there.”

There is a perceived consensus among participants that if tDCS effectiveness is demonstrated that they would opt for the stimulation intervention over pharmaceutical approaches.

Perceived compliance of tDCS versus medication

The duration and frequency of intervention “doses” and the maintenance of the treatment present some facets associated with the perceived compliance. Participants displayed a willingness and hope toward an intensive short term treatment option: “I would be more willing to put the time and energy into very intensive but shorter duration therapy versus the long haul [years of medication].” Another participant similarly notes “If you’re able to do something for a short span of time and see results as opposed to medication where you’re always switching doses and it’s going to be a lifelong thing, that’s a big factor in making the decision about which method we’re going to use.”

On the other hand, many participants indicated that the time it would take to see a positive change in their child’s behavior would also affect their acceptance: “Another factor is maybe how quickly you’re going to see results. . .Well if you’re doing this for 6 months then you might see a result, versus some people might say well I’ve been giving him medication for 2 to 3 weeks and I’m already going to start to see results.” Finally, one parent also considered the idea of accepting a combination of medication and tDCS. “You might be able to. . .use [tDCS] in combination with a lower dose of the medication to get the same or improved effectiveness.”

Participants generally expressed their compliance toward a short term intensive tDCS treatment compared to years of medication. That being said, the unspecific relief onset and currently unestalblished efficacy of tDCS is an important concern for parents as they consider tDCS as a treatment.

In summary, the analysis showed that the there are many components contributing to parents perceptions of the acceptability of tDCS. Acceptability of a new treatment is always relative to existing treatment. In general, families perceived tDCS as being acceptable when compared to medications. Parents hope for an alternative to medication that would be personally and socially more acceptable. The themes identified in the interviews seem to define the conditions for a new approach like tDCS to be acceptable: the new treatment should demonstrate efficacy and safety; be practical in terms of time, cost, coverage and availability; knowledge transfer to users is important to understand procedures and define expectation, and trust and reputation are imperative. Finally, the branding and terminology may be a barrier for adoption.

Discussion

Understanding the acceptability of a healthcare intervention is an imperative step in the process of translation and dissemination from research to clinical practice (Steele et al., 2008). At the 2020 NYC Neuromodulation Conference (https://youtu.be/PhzyPSZrZSo) several speakers explicitly discussed the unanswered community demand for tDCS and the onus of researchers and medical doctors to transfer evidence based tDCS protocols into community medicine. In the case of children with ADHD it is crucial to understand the parents’ perspectives on tDCS use in their child. Until now, perceptions of parents of children exposed to tDCS have not been investigated. The present study put the focus on the child and the parent. This led to several novel findings important for the understanding and acceptability of pediatric tDCS and its translation into practice. One finding that permeated throughout each interview was hope. In the healthcare literature, hope has often been viewed as an essential prerequisite to coping and adaptation to illness (Samson et al., 2009).

Hope provides the overarching recurring drive which connects the whole of participant’s decision making process. In the case of tDCS, this appears to begin with hope for a cure, or at least a more manageable short term intensive treatment option than medication. Actually enrolling their child in the study seemed to be a further extension of this as a hope to advance science. After experiencing tDCS first hand in the original trial, seeing the lack of side effects and learning about how it works, this manifested a new more specific hope: Hope that tDCS efficacy will be established and that it will become regulated through government health institutions. Ultimately, this translates to hope that tDCS can help their child and that it will provide better results than their previous options. This hope is the mirror image of the frustrations with medical treatment. Despite the medication, the children continue to struggle with symptoms, especially inattention, academic, and social difficulties. The burden on families remains considerable. Finally, even if medication reduces symptoms, concerns about side effects and being overly subdued remain among parents and adolescents (Sikirica et al., 2015). This hope is also the reflection of the desire to maximize symptom control and outcome found in preference studies (Nafees et al., 2014; Schatz et al., 2015).

Overall, parents find tDCS to be an acceptable treatment option. While this is encouraging from the point of view of parents, it is possible that the novelty of the treatment may reinvigorate their outlook toward their child’s prognosis. It is the responsibility of the medical and scientific community to not engender unrealistic expectations surrounding a novel treatment.

Perhaps one of the most important incidental findings is that acceptability, much like consent, is an ongoing process. It begins with the participant’s willingness to participate in the study, it becomes concurrent during the actual physical trial itself, and it becomes prospective in the context of continuing a trial or pursuing the treatment after the trial has ended. This is important because it highlights how tDCS acceptability is part and parcel to the ongoing decision making process of the participants.

After analyzing the data through the lens of Grounded Theory it became clear that many of the themes which emerged also closely coincided with the Theoretical Framework of Acceptability (Sekhon et al., 2017). The TFA describes seven criteria for understanding the acceptability of a new healthcare intervention: affective attitude, burden, ethicality, intervention coherence, opportunity costs, perceived effectiveness, and self-efficacy. Aligned with our results, the TFA also demonstrates that acceptability is an ongoing process.

Parents specifically expressed an interest in dosage of tDCS and the idea of combining or lowering medication dose by using tDCS as an adjunct. Notably, recent tDCS titration research from Samani, Agboada, Jamil, Kuo, and Nitsche (Samani et al., 2019) have begun to address these types of questions. Parents also hoped that tDCS would become properly regulated for neuropsychiatric care, primarily for insurance, accessibility, and safety reasons. To that end the recent tDCS Neuropsychiatric guidelines from Vicario & Nitsche (Vicario and Nitsche, 2019) are great steps forward. Lastly, parents were concerned that the accessibility of tDCS may be a challenge and some brought up the idea of using the device at home. Indeed, recent studies have found good compliance and outcomes using an at home tDCS approach (André et al., 2016; Charvet et al., 2018; Riggs et al., 2018). In addition, Knotkova and colleagues (Knotkova et al., 2019) have published a practical guideline for at home use.

Conclusion

Participants all had a direct experience of two tDCS sessions. With this experience, combined with the parents’ trust in the hospital conducting the research, and the lack of side effects, they were consistently partial to tDCS versus medication; viewing it as more manageable and revealing their hope toward the option of an intensive short term treatment for ADHD. This implies that families who trust their healthcare provider and are educated about tDCS would be more willing to try it as a treatment if it were prescribed. Participants’ acceptance of tDCS, however, came with a general contingency of establishing comparable efficacy to medication. Our conclusions are mostly limited to the primary school age range. Further research investigating tDCS acceptability may focus on younger preschool children or adolescent age groups where medication avoidance and refusal are more frequent, respectively.

Practice implications

This study provides insight regarding parents’ points of view of tDCS use in their child. Clinicians and researchers that plan to utilize tDCS, particularly in children, should consider this article as a guideline to relate to parents and to implement a protocol and environment that is considerate of their needs, their motivations, and their perceptions. As presented here, the parents’ points of view are imperative for acceptably translating tDCS from research to practice. Overall, it appears that parents are hopeful to pursue tDCS as a treatment option in their child once its efficacy is established and it becomes regularly available. This should alleviate apprehension surrounding tDCS use in children and encourage future research and clinical use.

Footnotes

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Derrick Matthew Buchanan

Amedeo D’Angiulli

Supplemental material

Supplemental material for this article is available online.

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