Conflicts of interest in invasive brain stimulation research

We read with great interest the recently published manuscript “A narrative review on invasive brain stimulation for treatment-resistant depression” by Dandekar et al.¹ Since major depressive disorder is highly prevalent, associated with significant impairment, and patients who do not respond to therapy face multiple challenges, it is of utmost importance to develop innovative and personalized interventions. The authors reviewed several studies on different treatment modalities, including case reports, cohort studies, open-label, and randomized clinical trials. The conflicting results and limitations of the current studies were discussed, with the authors concluding that “based on current data, invasive neurostimulation therapies may be considered a promising therapy for treatment-resistant depression.”

One important point not raised by the authors is the potential effect of the original investigators’ financial conflicts of interest and industry sponsorship of clinical trials on surgical interventions. Manufacturer-sponsored drug and device trials tend to report more favorable results and conclusions.² The potential impact of conflicts of interest on drug intervention studies and the allegiance effect³ in psychotherapy trials are commonly acknowledged and, more recently, bias in psychiatric neurosurgery research⁴ has been increasingly recognized, although it is still underreported. Invasive brain stimulation involves the use of devices to administer and monitor the clinical effect of treatment, and several companies have a great interest in developing and receiving approval from regulatory agencies.⁵

Due to the non-systematic nature of Dandekar et al.’s review,¹ no formal risk of bias assessment was performed for the included studies and no conclusions can be drawn about the influence of potential biases (including conflicts of interest) on positive outcomes in the reviewed trials. Future systematic reviews should address this important issue and shed further light and transparency on this important field of research. Meanwhile, the lack of data regarding conflicts of interest in narrative reviews should be considered and properly addressed as a limitation.

Acknowledgements

FAG has received research funding from the Brain & Behavior Research Foundation (NARSAD Young Investigator Award/P&S Fund Investigator), the Canadian Menopausal Society/Pfizer Research Award, Queen’s University Faculty of Health Science, Southeastern Ontario Academic Medical Organization (SEAMO), and Queen's University Department of Psychiatry internal grants. EB has received research funding from the PSI Foundation, Queen’s University Faculty of Health Science, Centre for Neuroscience Studies (CNS), Queen's University, and Department of Psychiatry internal grants. All these fundings are unrelated to the current manuscript.

References

• ¹
  Dandekar MP, Diaz AP, Rahman Z, Silva RH, Nahas Z, Aaronson S, et al. A narrative review on invasive brain stimulation for treatment-resistant depression. Braz J Psychiatry. 2022;44:317-30.
• ²
  Lundh A, Lexchin J, Mintzes B, Schroll JB, Bero L. Industry sponsorship and research outcome. Cochrane Database Syst Rev. 2017;2:MR000033.
• ³
  Dragioti E, Dimoliatis I, Fountoulakis KN, Evangelou E. A systematic appraisal of allegiance effect in randomized controlled trials of psychotherapy. Ann Gen Psychiatry. 2015;14:25.
• ⁴
  Cabrera LY, Boyce HMK, McKenzie R, Bluhm R. Conflicts of interest and industry professional relationships in psychiatric neurosurgery: a comparative literature review. Neurosurg Focus. 2018;45:E20.
• ⁵
  McIntosh T, DuBois JM, Perlmutter JS. Ethical challenges in the commercialization of neurotechnology: contending with competing priorities. AJOB Neurosci. 2022;13:60-2.

Publication Dates

• Publication in this collection
  25 Nov 2022
• Date of issue
  Nov-Dec 2022

History

• Received
  27 June 2022
• Accepted
  30 June 2022