External input for gait in people with Parkinson's disease with and without freezing of gait: One size does not fit all.

Cueing or feedback provided when gait deviates from a predefined goal (intelligent input) can now be provided with wearable technology for Parkinson's disease (PD). As people with and without freezing of gait (FOG) have distinct cognitive profiles, they may respond differently to various types of input. This study compared the effects of four input modalities during prolonged walking and explored the relationship with cognition, subjective preference, and FOG. Participants (15 with and 13 without FOG) walked 30 min while exposed to continuous cueing; intelligent cueing; intelligent feedback; or no input. Cueing consisted of metronome beats matched to comfortable cadence. Intelligent input represented bouts of ten beats indicating comfortable cadence (intelligent cueing) or an instruction to adapt gait speed (intelligent feedback) when cadence deviated from the comfortable target. Preference for one condition over the other was gathered. Freezers produced most stable gait under continuous cueing, but the majority favored intelligent feedback. Non-freezers showed no differences between conditions, but gait was more stable under intelligent input than in freezers. Interestingly, lower cognitive scores were related to worse gait during intelligent input, most prominently seen in freezers. These results suggest that cognitive ability is an aspect to take into account when deciding on the most appropriate cueing modality in different PD subgroups.