Spiral Tracing in Alzheimer’s Disease: Less Precise but not Slower

Abstract

BackgroundIn the search for novel Alzheimer’s disease (AD) biomarkers, motor functional outcome measures are potential candidates, as motor impairments can precede cognitive dysfunction. Whereas most motor behavioral research in Mild Cognitive Impairment (MCI) and AD has focused on gait function, fine motor skill is affected as well. Here, we use a digitized version of the Archimedes spiral test to assess a variety of speed and accuracy metrics of fine motor function in MCI and AD compared to cognitively normal (CN) individuals.Method46 CN, 23 MCI, and 17 AD participants traced an Archimedes spiral 3 times using a digital pen tablet. Spiral outcome measures included: path length, movement time, tracing speed (average and variance), radial distance (i.e., total deviation from the spiral template; average and variance), number of template crossings, and return movements.ResultLinear regression analysis adjusted for age and sex showed that those with AD had significantly larger radial distance than CN (p = .0056, eta^2 = .096). No other significant group differences were observed (all p>0.14, all eta^2<.028).ConclusionResults indicate that individuals with AD are less precise when tracing an Archimedes spiral, despite adequate movement speed and steadiness. These results support a wider examination of fine motor dysfunction in AD as an inexpensive and easily collectable biomarker in AD.