Delayed and More Variable Unimanual and Bimanual Finger Tapping in Alzheimer's Disease: Associations with Biomarkers

Vincent Koppelmans1,2, Marit F L Ruitenberg3,4, Sydney Y Schaefer5

  • 1Department of Psychiatry, University of Utah, Salt Lake City, UT, USA.

PubMed
Abstract

Insights

Fine motor skills, specifically finger tapping, are impaired in Alzheimer's disease (AD) and mild cognitive impairment (MCI). Tapping performance can help differentiate AD from controls, offering a potential biomarker.

Area of Science:

  • Neuroscience
  • Gerontology
  • Biomarkers

Background:

  • Fine motor function is understudied in mild cognitive impairment (MCI) and Alzheimer's disease (AD), despite known gross motor deficits.
  • Investigating fine motor impairments can provide new insights into the progression of cognitive decline.

Purpose of the Study:

  • To assess finger tapping performance in individuals with AD, MCI, and healthy controls.
  • To determine the relationship between finger tapping metrics and established AD biomarkers.
  • To evaluate the potential of finger tapping for classifying cognitive status (MCI/AD).

Main Methods:

  • Computerized unimanual and bimanual finger tapping tests were administered to 47 cognitively normal, 27 MCI, and 26 AD subjects.
  • Group differences were analyzed using permutation models.
  • Associations with biomarkers (amyloid-β PET, hippocampal volume, APOEɛ4) were examined via linear regression.
  • Machine learning (random forest) was employed to assess classification accuracy.

Main Results:

  • AD subjects exhibited slower reaction times and greater speed variability than controls, except in dual-task tapping.
  • MCI subjects showed deficits in reaction time and speed variability, particularly with non-dominant hand and dual-task tapping.
  • Finger tapping speed and variability correlated with hippocampal volume but not with amyloid-β deposition or APOEɛ4 status.
  • Random forest classification achieved 70% accuracy in distinguishing controls from AD, but struggled to differentiate MCI from controls or AD.

Conclusions:

  • Impaired finger tapping, characterized by slower reaction times and increased variability, is associated with MCI and AD.
  • Finger tapping deficits may reflect neuropathological changes related to hippocampal volume, suggesting later-stage disease involvement.
  • Finger tapping offers a cost-effective method for augmenting existing Alzheimer's disease biomarkers, particularly for differentiating AD from healthy controls.

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