APP and neurodegenerative disease: For instance, the “neurodegenerative diseases” cluster (Cluster 0) shows a significant peak in the early 2000s, reflecting a surge in research interest during that period, while the “amyloid precursor protein” cluster (Cluster 1) peaks around 2002, suggesting a focused research effort on the role of amyloid proteins in neurodegenerative processes, particularly in the context of HAND.