Table 1. Schematic diagram of participant timeline.

Assessments for all participants
	Baseline study visit	HD-DRUM training intervention (completed at home with support and reminders) or control time period	Follow-up study visit
	Day 1	8-week intervention period	End of week 8 (+ 2 weeks)
Cohort Descriptive information
MOCA*	X
TOPF	X
Self-report questionnaire
Patient Health Questionnaire-8	X		X
HD-DRUM participant evaluation survey			X
Paper and pencil tasks
Stroop task	X		X
Verbal fluency	X		X
SDMT	X		X
Categorical fluency	X		X
Verbal trails (letter-digit switching)	X		X
Computerised tasks
N-back Audio (letters)	X		X
N-back Visuospatial (square changing positions in grid)	X		X
N-back dual (audio and visuospatial)	X		X
Flanker task	X		X
Q-Motor assessments
Speeded finger tapping (left/right index finger)	X		X
Finger metronome tapping (left/right index finger)	X		X
Pointing and tapping (dominant hand)	X		X
Dual (pointing and tapping with dominant hand, speeded finger tapping with opposite hand)	X		X
Speeded foot tapping (left/right)	X		X
Metronome foot tapping (left/right)	X		X
Brain imaging
T1-weighted MPRAGE	X		X
msHARDI	X		X
qMT	X		X
mcDESPOT	X		X
HD-DRUM group
HD-DRUM training intervention supported by email and telephone reminders		X
Control group
Standard care, usual activities		X

HD, Huntington’s disease; mcDESPOT, multicomponent-driven equilibrium single pulse observation of T1 and T2; MOCA, Montreal Cognitive Assessment; msHARDI, multi-shell high angular resolution diffusion imaging; qMT, quantitative magnetisation transfer; SDMT, Symbol Digit Modalities Test; T1-MPRAGE, T1-weighted Magnetisation Prepared-Rapid Gradient Echo Sequence; TOPF, test of premorbid functioning