via Dr. Marc-Alexander Fluks Source: University Utrecht Date: May 11, 2021 URL: https://dspace.library.uu.nl/handle/1874/405927 https://dspace.library.uu.nl/bitstream/handle/1874/405927/Crowe (8158479) thesis.pdf Lumpers Versus Splitters: Analysing the Effects of Soothers on Fibromyalgia and Chronic Fatigue Syndrome Crowe, C. (2021) Faculty of Social and Behavioural Sciences Theses (Master thesis) Abstract The ‘Lumpers’ versus ‘Splitters’ debate has been central to the study of Functional somatic syndromes (FSS) for decades. Fibromyalgia (FM) and Chronic fatigue syndrome (CFS) share similar demographic and clinical characteristics; however, their aetiology and pathophysiology remain undetermined. Lumpers postulate that FM and CFS are simply different manifestations of a singular FSS, while ‘Splitters’ argue that they are separate FSSs. This study is part of a group project assessing the impacts of threats, soothers and drives on somatic symptoms. The current study focuses on the role of the soothing system, and investigates the potential ability of soothers to alleviate FM and CFS symptoms. Additionally, this study examines the experiential differences between these two FSSs, in order to add to the Lumpers versus Splitters debate. The sample consisted of FM and CFS patients (n = 804) aged 18 and over. Participants answered three questionnaires relating to the impact of soothers on their somatic symptoms, mental wellbeing, physical functioning, and how the syndromes affect their quality of life and overall health. The findings tentatively support the splitters perspective. Results revealed significant differences between CFS and FM regarding fatigue severity (the central symptom of CFS), and also indicated that balancing activities and relaxation was more important within CFS treatment in comparison to FM treatment. There were also differences in overall symptom severity, with FM patients being the least affected and patients with both FM and CFS being the most affected. This study highlights the potential utility of soothers within FM and CFS treatment. The results tentatively indicate that FM and CFS should be considered separate FSSs and provides a platform for future study in this area.