Learning effects of the sensory organization test as a measure of postural control and balance in Parkinson's disease

Introduction: Recent experiments examining balance in Parkinson's disease (PD) have used the sensory organization test (SOT) to measure postural control and balance. Use of the SOT raises the question as to whether people will improve after undergoing the test multiple times or if there is a learning effect plateau after multiple trials. The objective of this study was to determine whether there is a learning effect using the SOT in subjects with PD both fallers and non-fallers, and healthy controls. Methods: Nineteen subjects completed the study. Ten subjects with PD who were non-fallers (PD-Non-fallers), nine subjects with PD who were fallers (PD-Faller), and 10 healthy controls (Controls). Subjects completed 5 SOT testing sessions over a 3 week period. Those with PD were tested at the same time in their peak 'on' period. Results: The PD-Faller groups SOT composite score improved from session 1 to session 4 and 5. In the Control group the composite score improved from session 1 to session 5. There was no change from session 1 to session 5 in the PD Non-faller group. The PD-Faller group had significantly lower composite scores than our PD Non-faller group and our Controls. Our PD-Non-faller group scores were similar to Controls. Conclusion: Multiple baseline measures are usually recommended for any task used as an outcome measure. Our findings suggest that in PD subjects who are considered fallers that by the fourth session any improvement may be due to a learning effect. (C) 2015 Elsevier Ltd. All rights reserved.