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The neuropathology of probable Alzheimer disease and mild cognitive impairment

Julie A Schneider1, Zoe Arvanitakis, Sue E Leurgans

  • 1Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA. julie_a_schneider@rush.edu

Annals of Neurology
|September 11, 2009
PubMed
Abstract

Insights

Many individuals diagnosed with probable Alzheimer disease (AD) and mild cognitive impairment (MCI) exhibit mixed neuropathologies, highlighting the complex nature of these cognitive disorders.

Area of Science:

  • Neuropathology
  • Neurodegenerative Diseases
  • Cognitive Impairment

Background:

  • Mixed pathologies are frequently observed in older adults with dementia.
  • Understanding the spectrum of neuropathology in probable Alzheimer disease (AD) and mild cognitive impairment (MCI) is crucial.

Purpose of the Study:

  • To investigate the prevalence of single and mixed age-related neuropathologies in individuals with probable AD and MCI.
  • To characterize the neuropathological landscape of clinically diagnosed cognitive impairment.

Main Methods:

  • The study analyzed autopsied participants from the Religious Orders Study and Rush Memory and Aging Project.
  • Neuropathological examination included AD, macroscopic cerebral infarcts, and neocortical Lewy body (LB) disease.
  • Participants were categorized with probable AD, MCI (amnestic and nonamnestic), or no cognitive impairment.

Main Results:

  • Among 179 individuals with probable AD, 45.8% had mixed pathologies, most commonly AD with macroscopic infarcts.
  • In 134 individuals with MCI, 19.4% had mixed pathologies, with AD being present in 54.4%.
  • Macroscopic infarcts without AD were observed in 13.3% of amnestic MCI and 18.6% of nonamnestic MCI cases.

Conclusions:

  • Clinically diagnosed probable AD and MCI are pathologically heterogeneous.
  • A significant proportion of individuals with probable AD and MCI present with mixed pathologies.
  • These findings underscore the complexity of diagnosing and understanding cognitive decline.

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