Letter cancellation performance in alzheimer’s disease

Academic Article


  • Despite the frequency of visuospatial complaints in patients with dementia of the Alzheimer type, little is understood about the mechanisms underlying those symptoms. Letter-cancellation tasks were obtained from 50 patients with a clinical diagnosis of Alzheimer’s disease (AD). Twenty-two of the 50 subjects (44%) made a total of 36 errors in which they failed to cancel a target letter. There were no differences in mean age, education, gender, or Mini-Mental State Examination score between error-makers and those making no errors. The distribution of errors on the page was not random. When compared to previously reported results of healthy subjects on the same task, the proportion of AD subjects making errors was higher (44% vs. 26%), but the number of errors per error-maker did not differ. AD subjects demonstrated a high proportion of errors in the central region of the page, but did not show the normally expected performance bias to the left or distant half of the page. The pattern of errors reinforces past findings that deficits in the allocation and movement of visual attention across space occur in AD and that disorganization in visual search may contribute to AD patients' visuospatial dysfunction. © Lippincott-Raven Publishers.
  • Author List

  • Geldmacher DS; Doty L; Heilman KM
  • Start Page

  • 259
  • End Page

  • 263
  • Volume

  • 8
  • Issue

  • 4