Ires Ghielen

168 Chapter 9 (DDS) as a complication of dopamine replacement therapy, especially when the accompanied anxiety remains untreated [20, 21]. DDS is an impulse control disorder characterized by an addiction-like PD medication overuse [22]. One can also consider more advanced treatment options, such as Deep Brain Stimulation (DBS), continuous levodopa-carbidopa intestinal gel infusion, and continuous subcutaneous apomorphine infusion. These advanced treatment options are considered when PD patients experience debilitating response fluctuations and/ or dyskinesias in spite of optimal dopamine replacement therapy [23]. However, since PD is a neurodegenerative disease in which progressive decline is inevitable, patients eventually still develop symptom fluctuations and the abovementioned advanced therapies are considered rather invasive and/or contraindicated in some patients. It is therefore warranted to explore non-pharmacological and non-invasive treatments, to teach PD patients longterm coping strategies in order to deal with symptom fluctuations and interactions, as is also suggested by some of the studies included in our meta-analyses in chapter 6 [24-26]. To achieve acceptance of symptoms and healthy coping strategies, it is important to increase awareness of ones bodily symptoms, thoughts and emotions [27]. Especially, it is important to improve interoceptive accuracy, which refers to the accurate sensing of internal bodily changes, which includes both awareness and interpretation of bodily sensations [27]. Based on our clinical experience with PD patients that experience wearing-off related anxiety, we see inaccuracies in body awareness, which is an element of interoception. These inaccuracies can present themselves as either a hyperawareness or an unawareness. Hyperawareness refers to an excessive focus on bodily sensations and is characteristic in patients with an anxiety disorder, especially panic disorder [28-30]. A common factor in anxiety disorders is an attentional bias toward threat [28], and when one interprets bodily sensations as dangerous, hyperawareness on these sensations is a logical consequence and is evidenced to increase anxiety [30-32]. Unawareness can be seen as avoidance behavior, which can result in an overwhelming sense of anxiety (e.g. panic attack) when bodily sensations are so intense they cannot longer be ignored. Patients with functional neurological symptoms, chronic pain, and somatoform disorders show lower interoceptive accuracy [33-35]. In addition, reduced interoceptive accuracy was predictive of depressive symptoms [34] and correlated with symptom severity in these patients [33].