Parkinson's disease as a neuron disease

Abstract

The history of discoveries related to Parkinson's disease shows how difficult it was to conceive of an etiology based on anatomo-pathology in the 19th century. The difficulty in finding characteristic lesions led to overestimations of an hereditary etiology and an epistemological deadlock at a time when the central origins of some neurological diseases were being discussed, at the turn of the 20th century, and in the context of introducing the neuron theory in neurology. This was the challenge faced in the study of particular clinical cases and led neurologists to question the novel etiology, based on the selective destruction of special nerve cells, while the concept of “neuron disease” remained somewhat theoretical. However, by placing the anatomo-pathological studies of Parkinson's disease within the context of the evolution of the concept of neuron diseases, my intention is to clarify how this idea, defined mainly by other neurological diseases, influenced those studies. The focus is particularly on how the rationale behind those studies led to the identification of not only the neural centers involved, but also their associations and neuronal networks. In addition, there is an evaluation of how the neuron theory has shaped the dynamics of cytological studies, and the definition of neuronal pathways and their neurotransmitters, into the present etiological model of Parkinson's disease.