# Challenging or less challenging oral diadochokinetic tasks—what works best in Huntington disease? A cross-sectional study

## TL;DR

This study examines how speech tasks can detect motor impairment in Huntington disease and finds that alternating motion rate tasks are most effective.

## Contribution

The study identifies that alternating motion rate tasks in oral diadochokinesis are a sensitive and accurate measure of early motor impairment in Huntington disease.

## Key findings

- HD patients showed significantly slower and more irregular performance in both AMR and SMR tasks compared to controls.
- AMR performance had the highest accuracy (AUC = 95.0%) for detecting motor impairment in HD.
- Patients on antidopaminergic medications had slower motion rates but no change in regularity during oDDK tasks.

## Abstract

In Huntington disease (HD), speech alterations are common and may emerge before onset of chorea. Slow and irregular motion rates, i.e. altered oral diadochokinesis (oDDK), are a distinctive feature. This study investigated oDDK using alternating (AMR) and sequential motion rate (SMR) tasks in manifest HD and explored the impact of antidopaminergic medications (ADM).

Speech samples were acquired from 30 healthy controls (14 men; 27–78 years¸ age- and gender-matched to HD subjects) and 35 individuals with early-to-moderate HD (18 men; 22–76 years) phenotyped using standardized scales (UHDRS’99) and MR imaging to estimate disease severity. Acoustic analysis was used to quantify rate and regularity of oDDK. In an exploratory subgroup analysis, the impact of ADMs on oDKK was explored by comparing patients with and without ADMs (HD-ADM: n = 16; 8 men; 22–76 years; HD-nADM; n = 19; 10 men; 28–61 years).

HD patients were slower and more irregular in AMR and SMR tasks (p < 0.001) compared to controls. Analyses using area under the receiver-operating characteristic curve (AUC) showed the best characteristics for AMR (AUC = 95.0%). oDDK parameters correlated with measures of motor, cognitive and functional impairment and striatal atrophy. Patients on ADMs showed slower motion rates in both tasks (AMR p = 0.021; SMR p = 0.026), but unchanged regularity.

Decreased AMR performance alone captured early motor impairment accurately, reflects disease severity and is ADM-sensitive. Therefore, objective acoustic analysis of AMR performance is a simple measure which may serve as read-out to monitor disease progression, e.g. in clinical trials.

The online version contains supplementary material available at 10.1007/s00415-025-13310-x.