Association between olfaction and higher cortical functions in Alzheimer's disease, mild cognitive impairment, and healthy older adults

J Clin Exp Neuropsychol. 2017 Sep;39(7):646-658. doi: 10.1080/13803395.2016.1253667. Epub 2016 Nov 20.

Abstract

Introduction: Neural regions important for smell are proximal and closely connected to cortical areas that have been strongly implicated in higher order functions of value-based decision making and emotional memory. The integrity of these neural regions are affected in aging and neurodegenerative conditions. Two specific predictions follow from these neuroanatomical arrangements-namely, that olfaction would be associated with value-based decision making and with emotional memory.

Method: To test these predictions, we measured these different capacities in participants with presumed varying degrees of integrity of the relevant brain structures: specifically, 13 patients with Alzheimer's disease, 8 patients with mild cognitive impairment, and 20 healthy older adults. The participants completed detailed tests of olfaction, value-based decision making, emotional memory, and general cognitive ability.

Results: Olfactory functioning was significantly associated with emotional and nonemotional memory. The association was especially strong and consistent for memory recall with olfaction, explaining as much as 10% additional variance over and above general cognition. Olfactory functioning was not strongly or consistently associated with decision making over and above general cognition.

Conclusion: Olfaction is a strong predictor of memory recall. These findings may contribute to a better understanding of olfaction and specific cognitive domains known to be affected by aging and implicated in neurodegenerative disease.

Keywords: Decision making; Dementia; Emotions; Memory; Smell.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Aging / physiology*
  • Alzheimer Disease / physiopathology*
  • Cognitive Dysfunction / physiopathology*
  • Decision Making / physiology*
  • Emotions / physiology*
  • Female
  • Humans
  • Intelligence / physiology*
  • Male
  • Memory / physiology*
  • Olfactory Perception / physiology*