title: Visuomotor impairments in older adults at increased Alzheimer's disease risk.
abstract: OBJECTIVE
  Recent evidence suggests that visuomotor behaviors may be disrupted in the very early stages of Alzheimer's disease (AD). Here we propose that using kinematic measures under conditions that place demands on visual-spatial and cognitive-motor processing may provide an effective behavioral means to detect subtle changes associated with AD risk.
  
  
  METHODS
  To this end, we have tested 22 young adults (mean age = 26.4 ± 4.1) and 22 older adults (mean age = 64.3 ± 10.1) at low AD, and 22 older adults (mean age = 67.7 ± 11.3) at high AD risk (i.e., strong family history or diagnosis of mild cognitive impairment). Kinematic measures were acquired on four visuomotor transformation tasks (standard, feedback reversal, plane dissociated, and plane dissociated + feedback reversal) using a dual-touchscreen tablet.
  
  
  RESULTS
  Comparing participants at increased AD risk with both young and old healthy control groups revealed significant performance disruptions in at-risk individuals as task demands increased. Furthermore, we were able to discriminate between individuals at high and low AD risk with a classification accuracy of 86.4% (sensitivity: 81.8%, specificity: 90.9%).
  
  
  CONCLUSIONS
  We suggest that the impairments observed in individuals at increased AD risk may reflect inherent brain alteration and/or early neuropathology disrupting the reciprocal communication between hippocampal, parietal, and frontal brain regions required to successfully prepare and update complex reaching movements. Such impairment has the potential to affect activities of daily living, and may serve as a sensitive measure of functional ability in at-risk adults.
authors.affiliation: School of Kinesiology and Health Science, Centre for Vision Research, Neuroscience Graduate Diploma Program, York University, Toronto, ON, Canada.
authors.forename: Kara M
authors.initials: KM
authors.lastname: Hawkins
authors.affiliation: School of Kinesiology and Health Science, Centre for Vision Research, Neuroscience Graduate Diploma Program, York University, Toronto, ON, Canada.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Sergio
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000544:Alzheimer Disease / Q000150:complications* / Q000175:diagnosis; D001696:Biomechanical Phenomena; D003072:Cognition Disorders / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000209:etiology*; D009483:Neuropsychological Tests; D010468:Perceptual Disorders / Q000209:etiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Aging; Alzheimer's disease; geriatric assessment; motor skills; movement; neurodegenerative disorder