This is the first large‐scale randomised clinical trial investigating the effects of a cueing training programme delivered at home using a multimodality cueing device. The main findings indicate that nine sessions of cueing training demonstrated considerable improvement in gait and gait‐related mobility in people with Parkinson's disease, but that these effects were small and specific. The cueing method was widely accepted and well tolerated in a wide range of patients, ranging from Hoehn and Yahr stages II to IV, as evidenced by only one drop‐out.
The present findings showed that a period of training with cues in the homes of people with Parkinson's disease resulted in improvement of gait immediately after intervention. We found a significant increase in walking speed and step amplitude accompanied by a tendency to reduce step frequency. This finding is in agreement with earlier work, showing that the potential to generate a more normal gait pattern can be tapped in Parkinson's disease.7
When looking at freezers separately, a significant change on the Freezing of Gait Questionnaire after intervention was found, signifying a reduction of freezing severity. This is an important finding, as freezing is particularly resistant to drug treatment and often associated with falling.33
This result contradicts earlier work in which freezers were provided with a metronome for 1 week at home without clear benefits.34
In contrast, during the RESCUE trial, cueing therapy was provided by therapists, who used specific guidelines to set the cueing frequency to the needs of freezers, and instructed patients on how to prevent and overcome freezing in their daily environment for a 3‐week period.22
Increased rates of falls in people with Parkinson's disease are well documented and have been attributed to preserved mobility in this population.2,35
We were, therefore, concerned that any improvements in mobility due to therapeutic cueing could have resulted in an increased risk of falls. Our results, however, showed no evidence for this, but rather evidence of improved balance and increased confidence in the patients that they would not fall. Given the limited power to detect changes in fall rates using a fall‐diary method over a short time span, the present results need cautious interpretation.
Subjects were trained for 3 weeks with cues and were evaluated without wearing the device to see if the effects were maintained. The present results showed training effects in the absence of cues, indicating that some degree of motor learning is preserved in Parkinson's disease. Whereas most studies investigated the immediate benefits of cued performance, our findings confirm the limited evidence available of improved “uncued” performance after training with cues.6,8,12
The effects found in this study can be considered robust and not attributable to measurement error or learning effects. All but three outcome measures had established test–re‐test reliability in the home situation23
and the order of testing was randomised. To estimate the effects of intervention separately from carry‐over and time effects, the statistical analysis controlled for these factors, providing a conservative estimation of treatment effects.
The fact that intervention effects were small could reflect a limitation of cueing training in the home setting. However, current effects sizes are in line with those observed in recent meta‐analyses on physiotherapy in Parkinson's disease3,4
and in other conditions such as stroke.36,37
The limited effects may also be explained by the relatively short training duration. Training intensity rather than content was found to be a key factor in stroke research and may be equally crucial in Parkinson's disease.37
In this study, training intensity was stipulated by the maximum number of physiotherapy sessions at home allowed for reimbursement according to existing healthcare policies. This raises the question of what the optimal duration and intensity of cueing training is and how this should be delivered over time.
What actually constitutes clinically relevant results in rehabilitation of a chronic degenerative disorder is still unclear at this point. Possibly, the improvements of gait and balance were too small to carry over to ADL and perceived quality of life. Alternatively, the narrow focus of the intervention may have led to specific effects, as we showed that repetitive upper limb movements were not affected by cueing therapy. Equally, in other fields of rehabilitation lack of generalisation is a common feature.36,37
Training effects were not sustained at 6‐week follow‐up as a considerable reduction in most outcomes was apparent. Similarly, Nieuwboer et al38
showed a considerable deterioration at 12 weeks after training with cues and Thaut et al39
found a declining slope from 4‐week to 6‐week follow‐up. Other authors reported negligible reductions at 4–6 weeks after cueing training.12,40
The effect of placebo effects as a result of increased attention during therapy was not controlled for, which is a limitation of this study. Although the specificity of the results argues against a general effect of increased attention, effects of gait‐related attention rather than cueing cannot be ruled out. Previously, it was shown that gait training with auditory cues was more effective than training without cues and no training.8
Lack of Bonferroni correction and the fact that at tests 3 and 4 testers were aware of patients having received therapy, inherent to a repeated‐measures design, warrant careful interpretation of the results. However, testers were not unblinded to treatment allocation at any time point. The findings of this study cannot be generalised to people with Parkinson's disease who have significant cognitive decline and other comorbidities. Especially in the later disease stages, cues may overburden cognitive resources and increase fall risk.14
Future work should focus on determining such at‐risk patients. Equally, the possibility that cues may actually reduce attentional cost in patients who are not at risk requires further investigation. Recently, we found that during cued performance of dual tasks, gait parameters improved rather than deteriorated.19
Future studies, assessing cueing effects over a longer period of time, will be able to determine whether habituation occurs to the stimulus of the cue and verify our findings on fall risk associated with cueing over longer periods. In addition, the cost effectiveness of an extended therapeutic cueing programme possibly supplemented with a permanent cueing device needs further investigation. Although most patients preferred the auditory cueing modality (67%), a large number of them (33%) perceived somatosensory cueing as a well‐tolerated and discrete alternative. At present, auditory cueing alone can be provided at relatively low cost using metronomes with earphones or via digital music players.
We conclude that cueing training in the home situation has a small and specific benefit for managing gait and freezing in patients with Parkinson's disease. In addition, this study has highlighted important questions on how to deliver cueing training in the most optimal way.