'Migraines are associated with functional somatic syndromes'

Comorbidity in Migraine with Functional Somatic Syndromes, Psychiatric Disorders and Inflammatory Diseases: A Matter of Central Sensitization?

To approach the questions as to why migraine appears to be associated with functional somatic syndromes (FSSs) and whether central sensitization may be an underlying mechanism, the present study investigated (a) comorbidity with diagnoses of three FSSs, three psychiatric disorders, and three inflammatory diseases, (b) degree of mental health problems (stress, burnout, anxiety, depression and somatization), and (c) prevalence of ten cognitive/affective and nine airway symptoms in persons with migraine in the general population. From a randomized and stratified Swedish adult sample, questionnaire data were analyzed from 151 individuals with a diagnosis of migraine and 3,255 without migraine. The results showed (a) significant comorbidity in migraine with all FSSs, psychiatric disorders and inflammatory diseases, (b) significantly elevated scores on stress, burnout, anxiety, depression, and somatization, and (c) relatively high prevalence rates on almost all symptoms. Taken together, the results motivate future study of central sensitization as a mechanism underlying migraine.

Shared genetic factors underlie chronic pain syndromes

Chronic pain syndromes (CPS) are highly prevalent in the general population, and increasingly the evidence points to a common etiological pathway. Using a large cohort of twins (n=8564) characterized for chronic widespread musculoskeletal pain (CWP), chronic pelvic pain (PP), migraine (MIG), dry eye disease, and irritable bowel syndrome (IBS), we explored the underlying genetic and environmental factors contributing to CPS and the correlation between them. The sample was predominantly female (87.3%), with a mean age of 54.7 (±14.7) years. Prevalence of the different CPS ranged from 7.4% (PP) to 15.7% (MIG). For all CPS the within-twin correlation in monozygotic twin pairs was higher than in dizygotic pairs, suggesting a heritable component. Estimated heritability ranged from 19% (IBS) to 46% (PP). Except for MIG, we found significant pairwise phenotypic correlations between the CPS. The phenotypic correlation was highest between CWP and IBS (0.40; 95% confidence interval: 0.27 to 0.46). Excluding MIG from further analyses, cross-twin cross-trait correlations were higher in monozygotic compared with dizygotic twin pairs, suggestive of shared genetic factors between CWP, PP, IBS, and dry eye disease. Twin modeling analysis revealed the common pathway model as the model best explaining the observed pattern of correlation between the traits, with an estimated heritability of 66% of the underlying latent variable. These results are evidence of shared genetic factors in conditions manifesting chronic pain and justify the search for underlying genetic variants.