The aim of this study is to evaluate the ability of smartphone-based remote testing to meaningfully quantify signs, symptoms and impairments among participants with premanifest Huntington’s disease (HD) and manifest HD and compare them with healthy controls (HC).

A smartphone application comprising seven active tests (Symbol Digit Modalities Test [SDMT], Stroop Word Reading [SWR], Speeded tapping, Chorea, Balance, U-turn, 2-minute walk) and continuous passive monitoring is deployed in an observational study (Digital-HD) of participants with premanifest HD, manifest HD and HC.

Predefined active test measurements were aggregated over Weeks 5 and 6 post-screening to minimise practice effects. Group differences between HC, premanifest HD and manifest HD were analysed using the Kruskall–Wallis test and subsequent pairwise Mann–Whitney tests. In an exploratory analysis, a broader set of features was analysed for differences between HC and participants with premanifest HD. Recruitment for Digital-HD is ongoing. Preliminary data were analysed from 18 participants with premanifest HD, 15 with manifest HD and 19 HC.

Predefined digital tests generally had close correspondence with their commonly used in-clinic counterparts and these significantly differed between HC and the manifest group, as well as between the premanifest HD and the manifest HD groups (p=0.01-0.05 for U-Turn speed and 2-minute walk step frequency variability, p<0.01 for all other tests); however, no differences were observed in these tasks between HC and the premanifest HD group. The exploratory analysis identified several features with high face validity that significantly differed between HC and the premanifest group (e.g. tapping regularity in the speeded tapping test and drawing speed and accuracy in the Draw-a-shape test).