# Placebo in Functional Neurological Disorders: Promise and Controversy

## TL;DR

This paper explores the use of placebo in treating functional neurological disorders and the ethical issues it raises.

## Contribution

The paper provides a novel discussion on the ethical implications of using placebo in functional neurological disorders.

## Key findings

- Placebo effects in FNDs share neural mechanisms with active treatments.
- Placebo use raises ethical concerns about informed consent and patient autonomy.
- Placebo is considered safe but controversial for both diagnosis and treatment.

## Abstract

Placebo, nocebo, and lessebo effects are very frequent in patients with both neurological and psychiatric disorders. Interestingly, the neural mechanisms underlying placebo effects have been found to be the same as or similar to mechanisms targeted by active pharmaceutical interventions for many of these disorders. In the case of functional neurological disorders (FNDs), there are shared neural substrates between the central nervous system “placebo network” and the dysfunctional networks implicated in the pathophysiology. These networks are primarily involved in emotion regulation, stress responses, and the sense of self-agency. Therefore, placebo effects have also been discussed as therapeutic interventions in FNDs. Such an approach, however, has a variety of ethical implications evolving around informed consent, autonomy, nonmaleficence, beneficence, and justice. In this paper, we discuss the use of placebo, nocebo, and lessebo in FNDs as well as related ethical issues. Overall, the use of placebo in FNDs is currently still considered controversial both for diagnostic as well as therapeutic purposes. Although it is a safe and almost unique intervention, its use violates the core principles of medical ethics and doctor–patient interactions involving autonomy or openness in the therapeutic relationship.