Is the Apolipoprotein E Genotype a Biomarker for Mild Cognitive Impairment? Findings From a Nationally Representative Study

Charles J. Brainerd, Valerie F. Reyna, Ronald C. Petersen, Glenn E. Smith, Emily S. Taub

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Objective: Although the e{open}4 allele of the apolipoprotein E (APOE) genotype is a known risk factor for Alzheimer's dementia (AD), prior findings on whether it is also a risk factor for mild cognitive impairment (MCI) have been inconsistent. We tested two contrasting explanations: (a) an e{open}4-AD specificity hypothesis, and (b) a measurement insensitivity hypothesis. Method: The frequency of the e{open}4 allele was investigated in older adults (mean age > 70) with various types of cognitive impairment (including MCI) and various types of dementia (including AD) with the aging, demographics, and memory study (ADAMS) of the National Institute on Aging's Health and Retirement Study (HRS). The ADAMS controls sources of Type I and Type II error that are posited in the e{open}4-AD specificity hypothesis and the measurement insensitivity hypothesis, and it is the only nationally representative data set on aging and cognitive impairment. Results: e{open}4 was a reliable predictor of MCI, with a frequency of 32% in MCI subjects versus 20% in healthy control subjects. This link was specific to MCI because e{open}4 was not a risk factor for other forms of cognitive impairment without dementia. Conclusions: The results support the measurement insensitivity hypothesis rather than the e{open}4-AD specificity hypothesis and are consistent with recent research showing modest reductions in cognitive performance among normal functioning e{open}4 carriers.

Original languageEnglish (US)
Pages (from-to)679-689
Number of pages11
JournalNeuropsychology
Volume25
Issue number6
DOIs
StatePublished - Nov 2011

Keywords

  • APOE genotype
  • Alzheimer's dementia
  • Mild cognitive impairment

ASJC Scopus subject areas

  • Neuropsychology and Physiological Psychology

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