Combining Cognitive and Sensorimotor Assessments to Facilitate Detection of Age-Related Cognitive Decline

Early detection of cognitive decline is critical for reducing progression of neurodegenerative diseases. Bioimaging- and biofluids- based approaches are invasive and expensive; clinical screening tools have difficulties in discerning subtle cognitive changes. Eye tracking measures have been used to detect cognitive deficits effectively and reduction in sensorimotor performance may precede cognitive declines by several years. Therefore, we developed a combined cognitive and sensorimotor evaluation system by integrating an arm-hand exoskeleton and an eye-tracking device to facilitate the early detection of cognitive decline. Three combined cognitive and sensorimotor tests were investigated: combined anti-saccade motor test (CASMT), combined anti-saccade sensory test (CASST), and combined trail-making test B (CTMT-B). The combined tests were compared to conventional anti-saccade test (AST). Thirty-two healthy subjects, including 16 young subjects and 16 older adults, participated in the study. Results showed that the combined assessment better detected cognitive differences between older and young subjects than cognitive (eye-tracking) test alone. Specifically, 1) in CASMT, older subjects exhibited significantly longer eye movement latency than the young subjects (p < 0.001), while AST did not show such a difference. 2) in CASST, older adults showed longer latency in both eye (p = 0.003) and wrist (p = 0.005) movement than young subjects. 3) in CTMT-B, older adults took longer time to reach the targets (p < 0.001) and dwell longer at the targets (p < 0.001) than young subjects; older adults also showed more saccades during hand cursor reaching and dwelling, and lower cursor movement smoothness (p < 0.005). Furthermore, classification algorithms were used to predict participants' age groups, with the top six best-performing models confirming that sensorimotor outcome measures from CTMT-B, particularly the cursor movement smoothness, are highly influential, indicating the combined approach improves detection of cognitive changes. Correlation analysis further confirmed statistically significant negative correlation coefficients between MoCA results and outcome measures from CASMT and CTMT-B. The combined cognitive and sensorimotor tests showed more sensitive detections of cognitive and sensorimotor changes than the tests based on eye-tracking alone, and can potentially facilitate early detection of cognitive declines.