Staged decline of visual processing capacity in mild cognitive impairment and Alzheimer's disease

Neurobiol Aging. 2011 Jul;32(7):1219-30. doi: 10.1016/j.neurobiolaging.2009.07.012. Epub 2009 Aug 26.


Visual information intake was assessed with a whole-report task in patients with probable Alzheimer's disease (AD), mild cognitive impairment (MCI), and healthy elderly control subjects. Based on a theory of visual attention (TVA), four parameters were derived characterising different aspects of visual processing capacity: perceptual threshold, iconic memory, processing speed, and visual short-term memory (VSTM) storage capacity. Results indicated increased perceptual thresholds in MCI, and an additional decline in processing speed and VSTM storage capacity in AD. Cholinomimetic medication had beneficial effects on processing speed in AD patients. Perceptual thresholds were associated with disease duration, but not with cognitive measures, while the reverse was true for speed and VSTM measures. These results reveal a staged pattern of deficits affecting pre-attentive visual processing in MCI, and attentive processing in AD. It is compatible with the amyloid cascade hypothesis and suggests that impaired visual processing is a pathological feature present already at the MCI stage and might represent a distinct marker of upcoming AD independently from memory deficits.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Alzheimer Disease / diagnosis
  • Alzheimer Disease / drug therapy
  • Alzheimer Disease / physiopathology*
  • Cognition Disorders / diagnosis
  • Cognition Disorders / drug therapy
  • Cognition Disorders / physiopathology*
  • Cognitive Dysfunction / diagnosis
  • Cognitive Dysfunction / drug therapy
  • Cognitive Dysfunction / physiopathology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Perceptual Disorders / diagnosis
  • Perceptual Disorders / drug therapy
  • Perceptual Disorders / physiopathology*
  • Severity of Illness Index
  • Visual Perception / drug effects
  • Visual Perception / physiology