The Dual Task Ball Balancing Test and Its Association With Cognitive Function:Algorithm Development and Validation

Background: Dual task paradigms are thought to offer a quantitative means to assess cognitive reserve and the brain's capacityto allocate resources in the face of competing cognitive demands. The most common dual task paradigms examine the interplaybetween gait or balance control and cognitive function. However, gait and balance tasks can be physically challenging for olderadults and may pose a risk of falls. Objective: We introduce a novel, digital dual-task assessment that combines a motor-control task (the "ball balancing" test),which challenges an individual to maintain a virtual ball within a designated zone, with a concurrent cognitive task (the backwarddigit span task [BDST]). Methods: The task was administered on a touchscreen tablet, performance was measured using the inertial sensors embeddedin the tablet, conducted under both single- and dual-task conditions. The clinical use of the task was evaluated on a sample of375 older adult participants (n=210 female; aged 73.0, SD 6.5 years). Results: All older adults, including those with mild cognitive impairment (MCI) and Alzheimer disease-related dementia(ADRD), and those with poor balance and gait problems due to diabetes, osteoarthritis, peripheral neuropathy, and other causes,were able to complete the task comfortably and safely while seated. As expected, task performance significantly decreased underdual task conditions compared to single task conditions. We show that performance was significantly associated with cognitiveimpairment; significant differences were found among healthy participants, those with MCI, and those with ADRD. Task resultswere significantly associated with functional impairment, independent of diagnosis, degree of cognitive impairment (as indicatedby the Mini Mental State Examination [MMSE] score), and age. Finally, we found that cognitive status could be classified with>70% accuracy using a range of classifier models trained on 3 different cognitive function outcome variables (consensus clinicaljudgment, Rey Auditory Verbal Learning Test [RAVLT], and MMSE). Conclusions: Our results suggest that the dual task ball balancing test could be used as a digital cognitive assessment of cognitivereserve. The portability, simplicity, and intuitiveness of the task suggest that it may be suitable for unsupervised home assessmentof cognitive function.