Ires Ghielen

91 Longitudinal relationships between anxiety and motor symptoms Study Limitations Some limitations need to be acknowledged. Recall bias for the questionnaires is a limitation that must be considered. Also, the questionnaires contain different periods in time to which the questions apply, which might have altered the direct ‘in the moment’ symptom associations. For example, the FOGQ measures symptoms of freezing over the past week, the HADS measures anxiety symptoms over the past four weeks, which represents a longer period of time as compared to the FOGQ. Conclusions about cause-and-effect relationships can therefore not be made. Caution must be taken in generalizing the current findings to the general PD population, since this cohort had specific inclusion- and exclusion criteria. Starkstein and colleagues [59] indicate that increased depressive symptoms and anxiety often co-exists. In our study, PD patients were excluded when having a HADSD ≥ 8 which may have resulted in a study sample with relatively mild anxiety and mood disturbances. However, the results are robust within this large sample of PD patients and it is to be expected that an even stronger mutual interaction between FoG-FoF-anxiety could be found with higher levels of depressive and anxiety symptoms. Conclusion Our findings, based on a longitudinal design, show positive associations between FoG, FoF, and anxiety, suggesting that these symptoms interact and may aggravate each other. These reported interactions between motor and non-motor problems in PD underline the importance of an integrated interdisciplinary approach in diagnostics and treatment in these patients. Future perspectives The findings of our study contribute to increased awareness of the reciprocal interactions between motor and non-motor symptoms. This insight should lead to more multidisciplinairy oriented approaches in the diagnostics and treatment, such as the BEWARE training [5], aimed to learn how to deal with the motor and non-motor aspects of symptom fluctuations in PD. 5