Large-scale evidence for the validity of remote MoCA administration among people with cerebellar ataxia.

: For over half a century, studies of rare diseases using in-person cognitive tools have faced challenges, such as long study periods and small sample sizes (e.g.  = 10). The Montreal Cognitive Assessment (MoCA) was widely employed to assess mild cognitive impairment (MCI). We aimed to validate a modified online version of the MoCA in a large sample of a rare disease (population prevalence < .01%). : First, we analyzed 20 previous findings ( = 1,377), comparing the MoCA scores between large groups of neurotypically healthy (NH;  = 837) and cerebellar ataxia (CA;  = 540), where studies were conducted in-person. Second, we administered the MoCA in-person to a group of NH ( = 41) and a large group of CA ( = 103). Third, we administered a video conferencing version of the MoCA to NH ( = 38) and a large group of CA ( = 83). : We observed no performance differences between online and in-person MoCA administration in the NH and CA groups ( > .05, = 0.001), supporting reliability. Additionally, our online CA group had lower MoCA scores than the NH group ( < .001, Hedges'  = 0.68). This result is consistent with previous studies, as demonstrated by our forest plot across 20 previous in-person findings, supporting construct validity. : The results indicate that an online screening tool is valid in a large sample of individuals with CA. Online testing is not only time and cost-effective, but facilitates disease management and monitoring, ultimately enabling early detection of MCI.