Potential causal factors of CFS/ME: a concise and systematic scoping review of factors researched.

BACKGROUND: Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is understood as a complex condition, likely triggered and sustained by an interplay of biological, psychological, and social factors. Little oversight exists of the field of causal research. This systematic scoping review explores potential causal factors of CFS/ME as researched by primary studies. METHODS: We searched eight databases for primary studies that examined potential causal factors of CFS/ME. Based on title/abstract review, two researchers independently sorted each study's factors into nine main categories and 71 subordinate categories, using a system developed with input given during a 2018 ME conference, specialists and representatives from a ME patient advocacy group, and using BMJ Best Practice's description of CFS/ME etiology. We also extracted data related to study design, size, diagnostic criteria and comparison groups. RESULTS: We included 1161 primary studies published between January 1979 and June 2019. Based on title/abstract analysis, no single causal factor dominated in these studies, and studies reported a mean of 2.73 factors. The four most common factors were: immunological (297 studies), psychological (243), infections (198), and neuroendocrinal (198). The most frequent study designs were case-control studies (894 studies) comparing CFS/ME patients with healthy participants. More than half of the studies (that reported study size in the title/abstract) included 100 or fewer participants. CONCLUSION: The field of causal hypotheses of CFS/ME is diverse, and we found that the studies examined all the main categories of possible factors that we had defined a priori. Most studies were not designed to adequately explore causality, rather to establish hypotheses. We need larger studies with stronger study designs to gain better knowledge of causal factors of CFS/ME.

Attention deficit and hyperactivity disorder symptoms respond to gluten-free diet in patients with coeliac disease.

Introduction: Patients with coeliac disease commonly report symptoms of 'brain fog'. The aim of this study was to assess self-reported symptoms of impaired concentration in coeliac disease before and after treatment with gluten-free diet, compared with healthy controls and patient controls. Methods: Patients with newly diagnosed coeliac disease were included consecutively from two out-patient clinics. The patients completed the questionnaires Adult ADHD Self-Report Scale v1.1 Symptoms Checklist (ASRS), Hospital Anxiety and Depression Scale (HADS) and Gastrointestinal Symptom Rating Scale (GSRS) prior to start of a gluten-free diet and after at least 12 months on the diet. Patients with an established diagnosis of inflammatory bowel disease served as patient controls (n = 36). Health care personnel at Oslo University Hospital served as healthy controls (n = 60) and filled out ASRS and HADS. Results: A total of 31 newly diagnosed coeliac patients were included in the study. Of these, 26 patients met for follow-up and repeated the questionnaires. Prior to treatment, patients with coeliac disease had significantly higher scores than healthy controls on both the ASRS (p = .0014) and HADS (p=.0004). After a gluten-free diet, their scores improved and were not significantly different from healthy controls. There were no significant differences between patients with coeliac disease prior to treatment and patient controls with inflammatory bowel disease. Conclusion: Prior to treatment, coeliac disease patients reported significantly more symptoms than healthy controls on ASRS and HADS. The differences disappeared after a minimum of 12 months on a gluten-free diet.