Spatial navigation and the basal forebrain in Alzheimer's disease and other neurodegenerative diseases.

Neurodegenerative diseases such as Alzheimer's disease (AD) and Lewy body disease (LBD) are frequently associated with spatial navigation impairments. However, these impairments are less pronounced in frontotemporal dementia and limbic-predominant age-related TDP-43 encephalopathy. While basal forebrain degeneration occurs in all of these diseases, disruption of cholinergic pathways and related cholinergic deficits has been primarily observed in AD and LBD, and in both of these conditions, basal forebrain degeneration appears to be associated with spatial navigation deficits. In this review, we discuss current understanding of spatial navigation impairments in neurodegenerative diseases, with a particular focus on disease-related changes in the basal forebrain and their associations with impaired spatial navigation abilities in humans.