Spatial cognition in Parkinson disease

Visuospatial deficits have been found repeatedly in patients with Parkinson disease (PD). However, their precise nature and significance remain controversial. Whereas it is often asserted that primary visuospatial impairments begin early in the disease, others argue that poor performance on visuospatial tasks reflects methodological artifact. This article reviews research on spatial cognition in PD. Five categories of spatial functions are described: visual analysis and synthesis; facial recognition; judgment of direction, orientation, and distance; constructional praxis; and spatial attention. Proposed guidelines for future research include the use of conceptual rather than operational definitions of visual spatial ability, greater attention directed at separating spatial from nonspatial task components, and studies examining basic mechanisms underlying spatial vision.