Article Text

other Versions

PDF
Loss of basic lexical knowledge in old age
  1. Robert S Wilson1,2,3,
  2. Kristin R Krueger4,
  3. Patricia A Boyle1,3,
  4. David A Bennett1,2
  1. 1Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, Illinois, USA
  2. 2Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois, USA
  3. 3Department of Behavioral Sciences, Rush University Medical Center, Chicago, Illinois, USA
  4. 4Psychology Service, South Texas Veterans Health Care System, San Antonio, Texas, USA
  1. Correspondence to Dr Robert S Wilson, Rush Alzheimer's Disease Center, Rush University Medical Center, 600 South Paulina Ave, Suite 1038, Chicago, IL 60612; rwilson{at}rush.edu

Abstract

Background Basic lexical skills are hypothesised to be relatively preserved in mild dementia, but clinical studies have reported inconsistent results.

Methods More than 400 older Catholic nuns, priests and brothers recruited from groups across the USA completed annual evaluations for up to 15 years, died and underwent brain autopsy. Each clinical evaluation included administration of a 20-item word reading test and a 15-item vocabulary test, which were combined to form a composite measure of word knowledge. In a uniform neuropathological examination, Alzheimer's disease pathology was quantified with a composite index of plaques and tangles, and the presence of gross and microscopic cerebral infarctions and Lewy bodies was recorded.

Results The post-mortem level of Alzheimer's disease neuropathology was linearly related to rate of decline in word knowledge. Decline was nearly fourfold faster at a relatively high level of pathology (75th percentile) compared with a relatively low level (25th percentile). Neocortical (but not nigral or limbic) Lewy bodies and gross (but not microscopic) cerebral infarction were also associated with a more rapid decline in word knowledge. Effects for word reading and vocabulary were similar, except that gross cerebral infarction was associated with accelerated decline in vocabulary, but not in word reading.

Conclusion Common neuropathological changes associated with late-life dementia impair word knowledge in old age, calling into question the use of word knowledge tests to estimate premorbid cognitive ability.

  • Alzheimer's disease
  • Lewy bodies
  • cerebrovascular disease
  • cognition
  • post mortem
  • Received 18 March 2010
  • Revised 22 June 2010
  • Accepted 10 July 2010

Statistics from Altmetric.com

  • Received 18 March 2010
  • Revised 22 June 2010
  • Accepted 10 July 2010
View Full Text

Footnotes

  • Funding Support for this project was provided by federal grants from the National Institute on Aging: P30AG10161 and R01AG15819.

  • Competing interests None.

  • Ethics approval Ethics approval was provided by the Institutional Review Board of Rush University Medical Center.

  • Provenance and peer review Not commissioned; externally peer reviewed.

Request permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.