During this period, research increasingly treated degenerative neurological diseases as network disorders with selective neuronal vulnerability and systemic manifestations, rather than isolated motor syndromes. Work focused on linking clinical phenotypes to neuropathology and exploring autonomic involvement as a core dimension of disease, while genetic and familial patterns began to inform diagnostic frameworks. Methodologies blended detailed clinical characterization, postmortem analysis, and early genetic concepts, establishing a platform for integrative neuroscience in the late 20th century.