Idiopathic Parkinson's disease is generally described as a neurodegenerative pathology characterized by a progressive loss of dopaminergic neurons in the substantia nigra, responsible for impaired motor functions. Despite significant advances in understanding its biological mechanisms, a significant proportion of cases remain without a clearly identified organic explanation, which raising the question of other etiological avenues.In this context, the clinical work of Dr. Janice Hadlock makes an original contribution by suggesting the existence of a functional dysfunction of the dopaminergic system, not related to irreversible neuronal degeneration, but potentially reversible. This hypothesis, resulting from the observation of numerous cases in his clinical practice, calls into question the irreversible evolution of idiopathic Parkinson's disease and paves the way for a redefinition of clinical subtypes.This gives many patients hope of belonging to a reversible subtype.However, these observations have not yet been corroborated by a large-scale study, which limits their scientific significance. An in-depth multicenter survey would not only make it possible to estimate the prevalence of this functional form, but also to validate or refute the diagnostic criteria and therapeutic strategies it recommends. In the absence of such data, the distinction between organic Parkinson's and functional Parkinson's remains difficult to establish, but is plausible as also suggested by some scientific publications. The neurophysiological study of functional parkinsonian syndrome gains in depth when considering the autonomic mechanisms of the nervous system, particularly those related to fear and archaic reflexes. Building on the concept of defensive cascade, as described in article PMC4495877, ( https: //europepmc.org/article/pmc/4495877 ) it is possible to explore how these mechanisms can contribute to functional forms of the syndrome. These forms, like those observed by Dr. Hadlock, are characterized by a motor freeze and postural disorders that are not neuronal degeneration, but a neurological pattern that is incompletely reset and potentially reversible.This perspective paves the way for the integration of neurobehavioural models into the study of the disease, reinforcing the idea that functional Parkinson's could be, in a number of cases, the expression of a blockage in the defence circuits, rather than a neuronal death.Dr A. Vitiello
