ALLFTD Mobile App Balance and Finger Tapping Tasks: Task Description and Initial Reliability and Validity Findings

Abstract

AbstractBackgroundMotor disturbances are common in patients with a variety of neurodegenerative and neurological syndromes, such as Parkinson’s disease and Frontotemporal Dementia (FTD). Accurately quantifying motoric changes could enable earlier detection and monitoring of these syndromes, and remote quantification may allow for more frequent assessments and may improve access to research for underrepresented and geographically dispersed participants. With these benefits in mind, investigators from the ALLFTD consortium developed smartphone tests of balance and finger tapping speed. Here we present preliminary test‐retest reliability and associations with gold standard tests.MethodThe tasks were analyzed in two independent samples. The first was an in‐person cohort of healthy older adults (n = 7), mild cognitive impairment (MCI, n = 1) and FTD (n = 3) who completed the smartphone standing/balance and finger tapping tests (FTT) twice in person. The second sample included 31 ALLFTD participants with a range of clinical presentations (healthy older adults [n = 11], FTD [n = 5], MCI [n = 2], unknown [n = 13]) who were asked to complete the balance test three times over two weeks at home. The primary outcomes were total taps for the FTT and root mean squared acceleration for the balance test. Test‐retest reliability was calculated using an intraclass correlation coefficient (ICC); given the small sample size, outliers (n = 6) were removed from the balance test. We tested the association of smartphone FTT with the gold standard mechanical FTT and the balance task with the CDR®+NACC‐FTLD‐SB (disease severity) using Spearman’s correlations. A Wilcoxon‐sign rank test compared participants with motor features on the Progressive Supranuclear Palsy Rating Scale (PSPRS>0) to those without (PSPRS = 0).ResultThe smartphone FTT showed good test‐retest reliability (ICC = 0.78) and a strong correlation (r = 0.8,p<0.05) with mechanical FTT. The test‐retest reliability for the balance task was excellent for the remote sample (ICC = 0.97) and in‐person (ICC = 0.89) samples. In the remote sample, greater acceleration was correlated with higher CDR®+NACC‐FTLD‐SB (r = 0.7,p = 0.003), and participants with motor features on the PSPRS had higher acceleration than those without (W = 11,p = 0.04).ConclusionThese findings provide preliminary support for the reliability and validity of the ALLFTD Mobile App tests of motor function. Replication in a larger sample is required.