Ires Ghielen

164 Chapter 9 In clinical practice, patients with PD often present a complex variety of symptoms. Although PD is classified as a movement disorder, non-motor symptoms (including anxiety) are an important elements of the disease. In this thesis, it is hypothesized that in PD patients motor and non-motor symptoms have reciprocal influences and interact with one another, complicating diagnosis and treatment. In the first part of this thesis ( chapters 2 - 5 ) we focused on the associations and complex interactions between anxiety, other non-motor symptoms and motor symptoms in PD. We used the findings from these chapters, together with clinical experience and other research in the field, to develop a potentially better, multidisciplinary treatment for wearing-off related anxiety in PD. In the second part ( chapters 6 - 8 ) we focused on the efficacy of psychological and multidisciplinary treatment of motor and non-motor symptoms in PD. In the sections below, I summarize the results of each chapter of this thesis. Several methodological strengths and limitations of our work are considered, as well as the clinical implications of our findings. Finally, I discuss directions for future research and final conclusions. Summary of the results In chapter 2 we investigated the phenomenology of anxiety in PD by performing a principal component analysis to explore underlying symptom dimensions of anxiety as measured with the Beck Anxiety Inventory (BAI) [1]. We showed that the BAI consists of one affective and four somatic anxiety symptom subscales. We found significant associations between the somatic subscales and motor and autonomic symptoms, whereas the affective subscale showed a significant association with depressive symptoms and no association with motor or autonomic symptoms. The total BAI score also showed a significant association with severity of depressive symptoms. To investigate the generalizability of the findings in chapter 2, in chapter 3 we replicated these findings using a principal component analysis on the BAI in PD patients that were referred for neuropsychiatric assessment [2]. Again, we found one affective and four somatic anxiety symptom subscales, and a strong association between anxiety and depression. In a post-hoc analysis, the score on the affective subscale showed equal predictive value as compared to the total BAI score in predicting whether or not patients received an anxiety disorder diagnosis through psychiatric evaluation.