Cognitive Decline in Mild Cognitive Impairment With Lewy Bodies or Alzheimer Disease: A Prospective Cohort Study

•Do the initial patterns and long-term progressions of cognitive dysfunction differ in the MCI stages of Alzheimer disease (MCI-AD) or dementia with Lewy bodies (MCI-LB)?•Despite comparable global function, MCI-LB has worse executive and visual-perceptual function, and complex visual skills progressively deteriorate. MCI-AD has poorer recognition for learned information, and their visual function does not clearly decline over the MCI course.•MCI-LB and MCI-AD are characterized by differing profiles of cognitive dysfunction, and progress in a different manner.