Motor dysfunction as a marker for mild cognitive impairment and Alzheimer’s disease

Background Mild Cognitive Impairment (MCI) and Alzheimer’s disease (AD) are associated with motor impairments that can precede cognitive symptoms by several years. While prior studies suggest that such motor impairments may be an early disease marker and predict AD progression, most only included a single motor measure. Here, we tested the hypothesis that a broad motor assessment can distinguish MCI and AD from healthy controls (HC). Method To identify which measures jointly have the strongest predictive power we developed a comprehensive test battery assessing hand grip force, finger tapping speed (single and dual synchronized/alternating), Archimedes spiral and Trail Making Test drawing, and motor sequence learning. HC and MCI individuals additionally completed a 6‐meter walking test, timed up‐and‐go test, and Romberg balance test. Result So far 10 patients with amnestic MCI (70±5y; 5 males), 10 patients with AD (75±6y; 4 males), and 13 HC (69±6y; 5 males) completed the battery. We observed a pattern of mild to moderate motor deficits across motor domains in MCI patients compared to HC, including grip force, finger tapping and walking speed (medium‐to‐large effect sizes; eta2=0.08‐0.16). AD patients showed deficits in simple reaction time and drawing speed (large effect sizes; eta2=0.18‐0.2) compared to HC. Conclusion Our findings suggest that specific motor measures could be used as novel, inexpensive, non‐invasive biomarkers for dementia. If these cross‐sectional motor differences persist with larger samples, then it will be important to examine them longitudinally.