Neuroprotective Effects of Intermittent Theta Burst Stimulation in Parkinson’s Disease (NET-PD): A Study Protocol for a Delayed-Start Randomized Double-Blind Sham-Controlled Trial

Round 1

Reviewer 1 Report

This study attempted a randomized, double-blind sham-controlled trial using a different protocol for Parkinson’s patients to study the neuroprotective effects of Intermittent Theta Burst Stimulation. The experimental approach is rigorous, and the study protocol is written in detail and clearly. Implementing this study will require a high level of patient cooperation and compliance, and I look forward to seeing the study’s final results.

I have a few concerns about the content of the current article and the research protocol:

1. The authors expected to recruit patients between the ages of 20-80 years. This will inevitably include patients with young-onset PD (YOPD). It is also possible that patients with familial PD will be recruited. Since YOPD may differ from late-onset Parkinson’s disease (LOPD) in terms of clinical presentation, disease progression, and efficacy of drug therapy, and may affect the results of the current trial. Do investigators need to do a further evaluation (e.g., genetic testing), age stratification at randomization, or even exclusion for these YOPD patients?

2. Since the early-start groups (A1 and S1) and delayed-start iTBS groups (A2 and S2) in the study will both undergo iTBS in the second stage, the entire trial will compare the effect of iTBS in the first stage. What I understand is that the authors in this study wanted to see the neuroprotective effects of early-start iTBS. Perhaps the authors could add a “study hypothesis” to the Methods/Design to clarify how they would like to see the neuroprotective effect manifest itself. 

3. The study did not state whether the patients were drug-free when they underwent clinical assessments. If patients were evaluated while on medication, how do the investigators distinguish between the effects of medication adjustment and iTBS during the study?

 Minor Issues:

4. In the abstract, perhaps the authors will want to mark the full name before the first appearance of the abbreviation, such as PD and iTBS. 

5. Page 2, line 77: “Hope to provide a possible way...” The author may want to clarify who is hoping. 

6. Page 3, line 127, Please provide the full names of DBS and SCS. 

7. Page 7, lines 303-306. Please provide citations of TEMPO and ADAGIO investigations. 

8. Page 1, line 35: Parkinson’s disease (PD) 

9. Page 4, line 169: a “novel” form of excitatory TMS protocol 

10. Page 4, line 209: “a” reduced MEP. There are a few spelling and punctuation errors throughout the article; please double-check, including wording and punctuation (e.g., pseudo-stimuli or pseudo stimuli).

  Author Response

This study attempted a randomized, double-blind sham-controlled trial using a different protocol for Parkinson’s patients to study the neuroprotective effects of Intermittent Theta Burst Stimulation. The experimental approach is rigorous, and the study protocol is written in detail and clearly. Implementing this study will require a high level of patient cooperation and compliance, and I look forward to seeing the study’s final results.

I have a few concerns about the content of the current article and the research protocol:

Point 1：The authors expected to recruit patients between the ages of 20-80 years. This will inevitably include patients with young-onset PD (YOPD). It is also possible that patients with familial PD will be recruited. Since YOPD may differ from late-onset Parkinson’s disease (LOPD) in terms of clinical presentation, disease progression, and efficacy of drug therapy, and may affect the results of the current trial. Do investigators need to do a further evaluation (e.g., genetic testing), age stratification at randomization, or even exclusion for these YOPD patients?

Response 1: Thanks for the reviewer pointing this issue for us. The authors didn‘t take into account the variability of YOPD and familial PD. In order to reduce heterogeneity and improve the credibility of the results, the investigators decided to change the age range of the enrollment to 50-80 years, and age of diagnostic ≥ 50.

Point 2: Since the early-start groups (A1 and S1) and delayed-start iTBS groups (A2 and S2) in the study will both undergo iTBS in the second stage, the entire trial will compare the effect of iTBS in the first stage. What I understand is that the authors in this study wanted to see the neuroprotective effects of early-start iTBS. Perhaps the authors could add a “study hypothesis” to the Methods/Design to clarify how they would like to see the neuroprotective effect manifest itself. 

Response 2: Thanks for this advice. The author added a “Study hypothesis” section after outcome measures to manifest the expected results (line 401).

Point 3: The study did not state whether the patients were drug-free when they underwent clinical assessments. If patients were evaluated while on medication, how do the investigators distinguish between the effects of medication adjustment and iTBS during the study?

Response 3: Patients with or without medication are eligible to participate in this study. Patients' medications will be recorded during the evaluation and will be analyzed as covariates during data processing. Patients are required to be stable on antiparkinsonian medication during the intervention to avoid the effects brought by medication changes. Most patients take dopaminergic drugs as initial treatment, so being unmedicated is not a requirement for TMS intervention[1].

Minor Issues:

Point 4: In the abstract, perhaps the authors will want to mark the full name before the first appearance of the abbreviation, such as PD and iTBS. 

Response 4: Thanks for the reviewer pointing this issue for us. The author has corrected them in the article.

Point 5: Page 2, line 77: “Hope to provide a possible way...” The author may want to clarify who is hoping. 

Response 5: Thanks for the comments, the author has added the subject of this sentence in the article.

Point 6: Page 3, line 127, Please provide the full names of DBS and SCS. 

Response 6: Thanks for the comments, the author has corrected them in the article.

Point 7: Page 7, lines 303-306. Please provide citations of TEMPO and ADAGIO investigations. 

Response 7: Thanks for the comments, the author has corrected them in the article.

Point 8: Page 1, line 35: Parkinson’s disease (PD) 

Response 8: Thanks for the comments, the author has corrected it in the article.

Point 9: Page 4, line 169: a “novel” form of excitatory TMS protocol 

Response 9: Thanks for the comments, the author has corrected it in the article.

Point 10: Page 4, line 209: “a” reduced MEP. There are a few spelling and punctuation errors throughout the article; please double-check, including wording and punctuation (e.g., pseudo-stimuli or pseudo stimuli).

Response 10: We would like to express our appreciation to the reviewers for your carefulness. And the author has double-checked and corrected them in the article.

Reference:

1. Chung, C.L.; Mak, M.K.; Hallett, M. Transcranial Magnetic Stimulation Promotes Gait Training in Parkinson Disease. Ann Neurol 2020, 88, 933-945, doi:10.1002/ana.25881.

Reviewer 2 Report

The Authors have designed a very interesting clinical study utilizing a highly efficient, yet less time-consuming rTMS protocol - iTBS to investigate its potential effects on PD. Even though a study is well-designed and includes a large volume of parameters, there are some questions:

- If you predicted to enroll a total of 60 patients, at least several of them will be excluded from the study. The Authors also state that the number of 60 patients is the minimum to test their hypothesis. How will the problem of withdrawal be overcome?

- The material and methods section regarding experimental groups and study design should be more clear and more concise.

- It should be elaborated on why early-start and delayed-star cohorts exist. What is to be achieved through that design? 

- The Authors state that neuroprotective effects will be examined. This Reviewer could not find any parameter which could be used to determine neuroprotection. It should be rephrased.

- English requires extensive editing 

Author Response

The Authors have designed a very interesting clinical study utilizing a highly efficient, yet less time-consuming rTMS protocol - iTBS to investigate its potential effects on PD. Even though a study is well-designed and includes a large volume of parameters, there are some questions:

Point 1: If you predicted to enroll a total of 60 patients, at least several of them will be excluded from the study. The Authors also state that the number of 60 patients is the minimum to test their hypothesis. How will the problem of withdrawal be overcome?

Response 1: The investigators will try to avoid patient withdrawal in all aspects. At the stage of enrollment screening, the assessor will strictly follow the requirements and will emphasize the intervention setting (especially the duration of the intervention), and qualified individuals who are willing to participate in the long-term intervention are included in this experiment. During the course of the experiment, the investigator will contact the subjects every week to record their symptoms and urge them to follow up on schedule. If difficulties are encountered, try to solve the patient's complaints and get the patient's cooperation. If a patient decide to withdraw, the investigator wil ask and note the cause of the suspension and avoid similar problems during subsequent recruitment.

Point 2: The material and methods section regarding experimental groups and study design should be more clear and more concise.

Response 2: Thanks to reviewer for this suggestion, we reorganize and simplify the “Study Design” section and add a flow diagram (figure 1) to make the design more specific and consice.

Point 3: It should be elaborated on why early-start and delayed-star cohorts exist. What is to be achieved through that design? 

Response 3: Thanks for the reviewer pointing this issue for us. We have added the background of the early-start and delayed-start groups and the basis of the previous studies involving relevant designs in the “Introduction” section (line 90).

Point 4: The Authors state that neuroprotective effects will be examined. This Reviewer could not find any parameter which could be used to determine neuroprotection. It should be rephrased.

Response 4: The authors add some backup and detailed description for measuring neuroprotective effects in the "Outcome Measures" section and a “Study hypothesis” section for expected goal. According to the results of previous large delayed-start design disease-modifying drug studies, the neuroprotective effect can be commonly reflected by the difference in the changes of the UPDRS score before and after treatment between groups. Therefore, mean changes of UPDRS will be also used as the primary outcome indicator in this experiment.

Point 5: English requires extensive editing 

Response 5: Thanks to the reviewer for this advice. Following the editorial guidance, the authors chose the language editing service on https://www.mdpi.com/authors/english.

Reviewer 3 Report

• A brief summary (one short paragraph) outlining the aim of the paper, its main contributions and strengths.

“Neuroprotective effects of Intermittent Theta Burst Stimulation 2 in Parkinson's disease (NET-PD): A study protocol for a de-3 layer-start randomized double-blind sham-controlled trial”

The aim of this paper is to publish in advance the study protocol for a clinical trial of a specific kind of repetitive transcranial magnetic stimulation (Intermittent theta burst stimulation) for Parkinson disease patients. The statement is that this intervention not only ameliorates PD symptoms, but also reverse or stop disease progression.

From my point of view, authors fail to make the case from a theoretical point of view of why this hypothesis is true and worthy of a clinical trial. iTBS has been use in several conditions with some degree of success. However, it is important for the reader to have a body of references and actual preclinical and clinical work to support your claim, before any clinical trial could be considered.  The authors have to provide clear evidence of the neuroprotective effect in animal models and some theoretical framework, in order to explain the effect of a TMS in dying neurons.

The other general point lacking is the actual technical description of the iTBS in their patients. The paper should at least have a brief description of the technique, how this is implemented in the patient. Importants details that could allow reproduction of the technique. If a proper explanation is not included, at least some important papers should be cited in the article.  

This kind of technology can also produce  side effects. Authors should have done a safety study first (or at least mention articles that have done it!). If they or others have already done safety study, this has to be very clearly stated in the article. In addition, the technique applied (iTBS in this case) should be the same as the ones mentioned in the safety preliminary study.

• Comments in the text

Please find comments below in italics:

ABSTRACT

Line 16 “PD progresses rap-15 idly, and an additional proportion of patients are dopamine-resistant”:  

PD progress is variable, usually slow over several years. PD patients respond to dopamine. Lack of response to dopamine or dopamine agonist can lead to a new diagnostic in a patient with Parkinsonism: the first supportive criteria to the diagnostic of PD is :"Clear and dramatic beneficial response to dopaminergic therapy. During initial treatment, patient returned to normal or near-normal level of function"[Postuma et al.]

                         ARTICLE

Line 41 “PD is currently treated with a combination of pharmacological therapy, surgery, exercise therapy, neuron-regulation”

Neuron regulation? Could you define this concept?

Line 70 “…was there a definitive evidence of PD neuroprotection”

Which is the evidence that this particular external stimulation can produce neuroprotection? Are there any preclinical, animal model study that can support this claim?

Line 92 …”In stage1 (pseudo-controlled stage)”..

Stage 1= pseudo-controlled stage or intensive stage? Could you define this more clearly?

Line 97 “pseudo-stimuli in the first stage”

Could you define pseudo stimuli? Could you give more details?

Line 103:

Could you define more clearly, the stages and the periods? Possible a Diagram or a table could be appropriate here

Line 121:  “Exclusion criteria”

The absolute exclusion criteria should be a non-PD patient, according to the revised International Parkinson and Movement Disorder Society (MDS-PD) diagnostic criteria. The presence of any of the features that rules out PD like Unequivocal cerebellar abnormalities, Downward vertical supranuclear gaze palsy, selective slowing of downward vertical saccades etc ... should be cited or referenced as exclusion criteria [Postuma et al. (21)].

Line 156:

Could you include demographical criteria: men, women, age, age of diagnostic, severity, levodopa dosage etc?

 Line 166: “Randomization”…

Are the patients blind to treatment? Does she or he realize the coil changes or feels some tingling during real TMS?

  Line 169 “iTBS, as a noval form of excitatory TMS protocol, which is less time-consuming and more effective than standard rTMS”

 Please include here some reference in order to support this claim and move this sentence to discussion

 Line 190 “Paired pulse TMS (ppTMS) strategy”

 What is the goal of this experiment? For the localization of the motor strip?

 Line 242 “exosome alpha-synuclein (a-syn) will be measured using plasma”.

Very interesting test. Could you please explain how do you measure alpha syn exosomes in blood and provide the method and the reference?

Line 275 “Sample size and statistical analysis”

What is your expected attrition level? (patients lost from follow up )

 Line 302 “Results?”

 In the "Results" section of your protocol (both abstract and the main manuscript body), you should include explicitly the current status of the project (e.g. "Funded in X, data collection started in Y and is expected to complete in Z | data collection has been completed in Z)")

      Author Response

Point 1: ABSTRACT

Line 16 “PD progresses rapidly, and an additional proportion of patients are dopamine-resistant”:  

PD progress is variable, usually slow over several years. PD patients respond to dopamine. Lack of response to dopamine or dopamine agonist can lead to a new diagnostic in a patient with Parkinsonism: the first supportive criteria to the diagnostic of PD is :"Clear and dramatic beneficial response to dopaminergic therapy. During initial treatment, patient returned to normal or near-normal level of function"[Postuma et al.]

Response 1: Thanks for the reviewer pointing this issue for us. The author corrects inappropriate content in the “abstract” and “introduction” sections. Despite that dopaminergic therapy is the first strategy for PD, patients who are clinically insensitive to medication and whose symptoms fail to improve are commonly seen.

Point 2: Line 41 “PD is currently treated with a combination of pharmacological therapy, surgery, exercise therapy, neuron-regulation”

Neuron regulation? Could you define this concept?

Response 2: My apologize for lack of rigor. “Neuron regulation” here is expressing the same meaning as neuromodulation, such as TMS, tDCS, VNS, and DBS. “Neuron regulation” is not commonly used and is not quite appropriate, the author changes it to “neuromodulation” in the text.

Point 3: Line 70 “…was there a definitive evidence of PD neuroprotection”

Which is the evidence that this particular external stimulation can produce neuroprotection? Are there any preclinical, animal model study that can support this claim?

Response 3: Thanks for the reviewer pointing this issue for us. The authors list some animal model neuroprotection studies in the “Introduction” section, but the expression is not detailed enough, so the we rework the language and add some findings to support this claim (line 77-85).

Point 4: Line 92 …”In stage1 (pseudo-controlled stage)”..

Stage 1= pseudo-controlled stage or intensive stage? Could you define this more clearly?

Response 4: To be specific , “Stage 1”= pseudo-controlled stage, “Stage 2”=active treatment stage and “Phase 1”= intensive phase, “Phase 2”= maintenance phase. The authors supply a concrete discription and a diagram in “Study design” section (line 131, figure 1).

Point 5: Line 97 “pseudo-stimuli in the first stage”

Could you define pseudo stimuli? Could you give more details?

Response 5: Like placebo control group in drug experiments, “pseudo stimuli” is the control group to active iTBS group. Detailed in “iTBS Intervention and follow-up” section (line 269).

Point 6: Line 103: Could you define more clearly, the stages and the periods? Possible a Diagram or a table could be appropriate here

Response 6: Thanks to reviewer for this suggestion, the author adds a flow diagram (Figure 1. Schematic representation of study outline and visits.) to depict the study design.

Point 7: Line 121: “Exclusion criteria”

The absolute exclusion criteria should be a non-PD patient, according to the revised International Parkinson and Movement Disorder Society (MDS-PD) diagnostic criteria. The presence of any of the features that rules out PD like Unequivocal cerebellar abnormalities, Downward vertical supranuclear gaze palsy, selective slowing of downward vertical saccades etc ... should be cited or referenced as exclusion criteria [Postuma et al. (21)].

Response 7: Thanks to reviewer for reminding us, the author add this item in “Exclusion criteria”.

Point 8: Line 156:

Could you include demographical criteria: men, women, age, age of diagnostic, severity, levodopa dosage etc?

Response 8: Demographic information is partially described in the “inclusion criteria”, age 50-80, age of diagnostic ≥ 50, male or female, Hoehn -Yahr stage ≤ 4, with or without medication, maintaining medication stability during the study period.

Point 9: Line 166: “Randomization”…

Are the patients blind to treatment? Does she or he realize the coil changes or feels some tingling during real TMS?

Response 9: Yes, all the patients blind to treatment. The pseudo-stimulation coil looks exactly the same as the real iTBS coil and emits the same sound and vibration sensation during the stimulation process, but there is no actual stimulation effect. Coil replacement will be completed before the patient enters the treatment room. This ensures that subjects are unaware of the grouping. Specific descriptions are added in the “Randomization and blinding” section.

Point 10: Line 169 “iTBS, as a noval form of excitatory TMS protocol, which is less time-consuming and more effective than standard rTMS”

Please include here some reference in order to support this claim and move this sentence to discussion

Response 10: The authors have moved this sentence to the “Discussion” section and added supporting literature based on this comment.

Point 11: Line 190 “Paired pulse TMS (ppTMS) strategy”

What is the goal of this experiment? For the localization of the motor strip?

Response 11: Paired-pulse transcranial magnetic stimulation (ppTMS) is a non-invasive method utilized to measure GABAergic activity within M1 to probe inhibitory and excitatory networks, which is a common TMS-combined test allows for easy and quick measurements before and after treatment (line 288).

Point 12: Line 242 “exosome alpha-synuclein (a-syn) will be measured using plasma”.

Very interesting test. Could you please explain how do you measure alpha syn exosomes in blood and provide the method and the reference?

Response 12: The steps of assessing exosome a-syn broadly include exosome isolation, incubation, electron microscopy imaging, western blotting and mass spectrometry analysis. Detailed instructions are added in the “Blood test” section (line 355-367).

Point 13: Line 275 “Sample size and statistical analysis”

What is your expected attrition level? (patients lost from follow up)

Response 13: Delayed-start drug trials are over 1 year with high dropout rates around 15%-25%[1-3]. TBS interventions are generally shorter than drug study experiments, and the dropout rate is 0%-13%[4-6]. Combining the results of the above previous studies, the patient dropout rate of NET-PD is about 10%.

Point 14: Line 302 “Results?”

In the "Results" section of your protocol (both abstract and the main manuscript body), you should include explicitly the current status of the project (e.g. "Funded in X, data collection started in Y and is expected to complete in Z | data collection has been completed in Z)")

Response 14: Thank for this suggestion from the perspective of the overall article. The authors add the “Results” in the abstract and main body. The NET-PD project was funded in March 2022, data collection began in July 2022, and is currently in the recruitment phase with 2 PD patients already enrolled. Data collection expected to be completed in June 2024 and data analysis in October 2024.The results are expected for publications in December 2024.

Reference：

1. Group, P.S. A controlled, randomized, delayed-start study of rasagiline in early Parkinson disease. Arch Neurol 2004, 61, 561-566, doi:10.1001/archneur.61.4.561.
2. Schapira, A.H.; McDermott, M.P.; Barone, P.; Comella, C.L.; Albrecht, S.; Hsu, H.H.; Massey, D.H.; Mizuno, Y.; Poewe, W.; Rascol, O.; et al. Pramipexole in patients with early Parkinson's disease (PROUD): a randomised delayed-start trial. Lancet Neurol 2013, 12, 747-755, doi:10.1016/s1474-4422(13)70117-0.
3. Olanow, C.W.; Rascol, O.; Hauser, R.; Feigin, P.D.; Jankovic, J.; Lang, A.; Langston, W.; Melamed, E.; Poewe, W.; Stocchi, F.; et al. A double-blind, delayed-start trial of rasagiline in Parkinson's disease. N Engl J Med 2009, 361, 1268-1278, doi:10.1056/NEJMoa0809335.
4. Benninger, D.H.; Berman, B.D.; Houdayer, E.; Pal, N.; Luckenbaugh, D.A.; Schneider, L.; Miranda, S.; Hallett, M. Intermittent theta-burst transcranial magnetic stimulation for treatment of Parkinson disease. Neurology 2011, 76, 601-609, doi:10.1212/WNL.0b013e31820ce6bb.
5. Trung, J.; Hanganu, A.; Jobert, S.; Degroot, C.; Mejia-Constain, B.; Kibreab, M.; Bruneau, M.A.; Lafontaine, A.L.; Strafella, A.; Monchi, O. Transcranial magnetic stimulation improves cognition over time in Parkinson's disease. Parkinsonism Relat Disord 2019, 66, 3-8, doi:10.1016/j.parkreldis.2019.07.006.
6. Lang, S.; Gan, L.S.; Yoon, E.J.; Hanganu, A.; Kibreab, M.; Cheetham, J.; Hammer, T.; Kathol, I.; Sarna, J.; Martino, D.; et al. Theta-Burst Stimulation for Cognitive Enhancement in Parkinson's Disease With Mild Cognitive Impairment: A Randomized, Double-Blind, Sham-Controlled Trial. Front Neurol 2020, 11, 584374, doi:10.3389/fneur.2020.584374.

Round 2

Reviewer 3 Report

The article content has been improved since the last review. I would like to see two things included in the last version: First  the  references and/or the authors own experience about the safety of the procedure. We know that TMS has some side effects(i.e. seizures) that can be potentiated by this approach iTBS. The second thing is an improvement in the english language and style. Maybe you should send the manuscript to professional proof a reading expert to increase the paper quality. If those requisite are met: I would recommend.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf