Hallmarks of the overlapping syndromes include non-nociceptive pain, fatigue, memory difficulties, and dysfunction of visceral organs, Clauw, 2002. Dr. Bell has written a list of symptoms of ME/CFS, cfs.symptoms.bell04.txt.
The following syndromes are regarded as overlapping CFS/ME: Fibromyalgia (FM), Post-Polio Syndrome (PPS), Gulf War Syndrome (GWS), Multiple Chemical Sensitivity (MCS), Irritable Bowel Syndrome (IBS), temporomandibular disorder (TMD), Lupus (SLE) and Interstitial Cystitis (IC). The coexistence of FM and TMD with MMP is high, leblebici.etal06.txt.
Whiplash is definitely also an overlapping syndrome, a 2002-paper which discuss Whiplash/FM from a psychological point of view, Ferrari, 2002. The development of persistent pain and psychological morbidity after motor vehicle collision: integrating the potential role of stress response systems into a biopsychosocial model, mclean.etal05.txt.
Lyme disease can be mistaken for CFS, shor06.txt.
More seldom is mentioned vulvodynia, arnold.etal06.txt.
Studies on Overlap
Somatic comorbidities of irritable bowel syndrome: a systematic analysis, riedl.etal08.txt. CFS, FM, and TMD share key symptoms, Aaron et al., 2000 (txt), and Ta et al., 2002. Dr. Jason's group studied the degree of overlap between CFS, FM and MCS, Jason et al., 2000, and, Taylor et al., 2001. A thorough review from Dr. Klimas group on the overlap between FM and other syndromes, Patarca-Montero, 2001, and Dr. Buchwald's group found more overlap between CFS and FM than expected, Sullivan et al., 2002. Overlap between FM and overactive bladder syndrome, soyupek.etal07.txt.
Belgian researchers suggest that CFS and FM are aspects of the same disease, nijs.etal.04.txt, nijs.etal04.pdf. A review of muscular pain in CFS, meeus.etal06.txt, meeus.etal.06.txt, meeus.etal06.pdf. Is CFS a connective tissue disorder? vanderputte.etal05.txt.
CFS and rheumatic diseases overlap in terms of salivary gland damage, Woo et al., 2000. FM overlaps with rheumatic diseases, in this case Systemic Lupus, akkasilpa.etal05.txt. Fatigue is a symptom shared by all rheumatic diseases, zautra.etal06.txt.
From a psychiatric point of view overlapping symptoms imply common, but unexplained mechanisms of disease, as in 'unexplained clinical conditions', Aaron & Buchwald, 2001. The 'UK-psychiatric-approach' to the syndromes, meaning "functional somatic", Nimnuan et al., 2001 (abstr), Nimnuan et al., 2001 (paper). A study by Dr. Jason documented co-existence of CFS, FM and psychiatric disease, but referred to it simply as comorbidity, Jason et al., 2001. One review found co-morbidity of IBS and other syndromes, and suggested a psychological explanation, Whitehead et al., 2002. A population-based Swedish study, kato.etal06.txt, kato.etal06.pdf. FM women have increased risk of metabolic syndrome, loevinger.etal06.txt.
The above evidence has led to the hypothesis of one single syndrome, Ciccone & Natelson, 2003 (short), Ciccone & Natelson, 2003, Ciccone & Natelson, 2003 (pdf). These authors however, question the assumption that all patients with CFS suffer from the same underlying disorder, ciccone.etal08.txt, ciccone.etal.08.txt, ciccone.etal08.pdf.
The Single Syndrome hypothesis is supported by the finding of common cytokine abnormalities, vandemerwe.etal03.txt. FM and SLE may have involvement of N-methyl-d-aspartate (NMDA) and neurokinin receptor systems in common, staud06.txt.