To our knowledge, this is the first intervention trial using an ABF system for training posture and balance in patients with PD. In this pilot study, we demonstrated that ABF training in patients with PD is feasible and that it appears to be well accepted. Adherence to the training protocol was high with no attrition. All patients also reported satisfaction and enjoyment during the training program while the therapist commented on the ease of use of the device. Some of the training sessions were conducted in the patients' home-environment with the rationale that behavior and performance may be altered in a clinical setting with unfamiliar surroundings and that training in the home could address the particular needs of each patient. The sessions at home were similar to the lab sessions in the provided exercise program and tasks performed. Patients commented that they felt comfortable during the home sessions and that they could foresee a need for such training in the future.
This training program demonstrated some potential therapeutic effects on postural control and psychosocial aspects of the disease. Small, but positive changes were observed in the BBS, 5 chair rise test, TUG and the pull test of the UPDRS rating scale. Components of these tasks were trained during the intervention and therefore, these effects could be considered a result of task specific training. Although statistically significant, the improvements on the BBS revealed only a mild change in actual function. This may be due to the fact that the patients had relatively high scores at baseline suggesting that the measure may not have been sensitive enough to detect minor changes in balance tasks. Some of these improvements were also observed at follow-up demonstrating initial support for retention of the effects of ABF training even in the presence of neurodegeneration.
Patients also reported improved mood after training however, without a control group, it is difficult to know if the improvement should be attributed to the participation in this research study and its weekly routine, or if this was a beneficial by-product of the ABF training. Interestingly, the sub items that were affected by the training on the quality of life questionnaire (PDQ-39) were mobility, ADL and cognition, which are all consistent with the specific training goals and the particular training effects. Although scores on the Activities-specific Balance Confidence scale (ABC) did not change, anecdotally, patients described that they were able to move more freely, with less assistance and more confidence after the training. Once more, this finding could be attributed to the insufficient sensitivity of the ABC as the sections that were scored low initially on this scale were not addressed in this training protocol.
A key limitation of this study is the small sample size. The present study aimed to explore if this training method is feasible for patients with PD. As such, the findings are encouraging. Future studies should include a larger sample of patients and compare them to an active control group. Training with the ABF device teaches participants new strategies of movement that could be applied in real life situations. In this sense, the ABF may have an advantage over other technologies used in PD such as external cueing, by enhancing motor learning through feedback on knowledge of performance and knowledge of results. Although, there is evidence in the literature on the positive effects of cueing strategies on gait in PD [32
], gait training with the ABF has yet to be examined. Further studies are needed to look at the possibility of using ABF for independent, home training, and specifically for the purpose of improving gait
in PD. The findings of our study should also encourage therapists to perform ABF-based physical training in other age-associated disorders such as elderly with higher level gait disorders and older adults with high fall risk or with Mild Cognitive Impairment.
In conclusion, the results presented here demonstrate that ABF-based physical training for posture and balance in PD is feasible and associated with quantitative improvements. This may be viewed as a promising first step to implement home-based training strategies for patients with PD, a cohort which does not yet have sufficient therapeutic options for improving postural instability and alleviating gait disturbances.