We investigated psychological distress in patients with RLS in a cross-sectional study. This study has two major findings: Firstly, RLS patients who are untreated show slightly elevated psychological distress in the domains somatisation, compulsivity, depression, and anxiety compared to representative values. Second, the psychological distress increases with the experience of frustrane treatments such as loss of efficacy and augmentation and can lead to clinically relevant psychological problems particularly in the domains of compulsivity and anxiety. The study yielded new evidence on psychological impairment of patients with RLS as to our knowledge no other study investigated the whole spectrum pf psychopathology in RLS. Of particular interest is our finding of elevated somatisation, which is frequently found in chronic disorders [18, 26–30]. Corresponding to this finding, a recent study described a high rate of somatoform disorders (41%) and of chronic pain (34%) in RLS patients , and these comorbidities contributed to an unfavourable RLS treatment outcome . A further interesting finding is the relatively high score for compulsive behaviour, particularly in treated patients. This finding is in line with recent observations reported in connection with the occurrence of impulse control disorders, such as pathological gambling, shopping addiction, and drug hoarding during dopaminergic treatment in Parkinson's disease  and RLS [33, 34]. Reported drug hoarding and increased medication consumption that was associated with augmentation  corresponds to our observation of elevated compulsivity in augmented patients. Elevated depression and anxiety scores have been reported in RLS (for review see ), our findings are in line with these studies.
The psychological burden appears to be the highest in patients with augmentation followed closely by those experiencing loss of treatment efficacy. An explanation for this, though not specific to RLS, may be that frustration encountered during the course of treatment may promote feelings of helplessness and negative cognitions such as catastrophic thoughts.
The main limitation of the study is its cross-sectional design. Therefore, it remains difficult to judge whether poor long-term responders to treatment may be predisposed by psychological factors to the development of psychological problems or whether the treatment itself, including dopaminergic therapy, may impact psychological functioning. Longitudinal studies observing the change in burden experienced over time in routine care are needed. In future studies the influence of comorbid chronic disorders and intake of non-RLS specific medications should be considered. A more detailed assessment of treatment problems is also required. A selection bias may exist in the centres Bremen and Schwerin, where patients with incomplete questionnaires were not included in the study. Comparison of the populations in the centres revealed, however, no differences in the main characteristics such as age, gender, psychological symptoms, or RLS severity.
Severely affected RLS patients show psychological impairment with abnormalities in multiple psychological domains. These particularly interesting abnormalities should be considered in the treatment of RLS patients. For some severely affected patients, psychological support may be necessary. Patients can benefit from being educated in coping strategies that enable the patients to deal better with the disorder and prevent exacerbation of psychological symptoms [36, 37]. Cognitive interventions may help in better coping with depressive and anxiety symptoms and mindfulness-based exercises [36, 37] may reduce the sympathetic hyperactivity described in RLS . In a pilot study, such strategies were applied successfully to a group of patients with mild to moderate RLS [36, 37].