Objective: Functional somatic syndromes (FSSs) have often been linked to psychopathology. The aim of the current study was to compare prevalence rates of psychiatric disorders among individuals with chronic fatigue syndrome (CFS), fibromyalgia (FM), and irritable bowel syndrome (IBS).
Methods: This study was conducted in 94,516 participants (mean [standard deviation] age = 44.6 [12.5] years, 58.7% women) of the general-population cohort LifeLines. FSSs were assessed by self-reports. Mood disorders (i.e., major depressive disorder and dysthymia) and anxiety disorders (i.e., generalized anxiety disorder, social phobia, panic disorder with/without agoraphobia, and agoraphobia) were assessed by means of the Mini International Neuropsychiatric Interview. Risks on psychiatric disorders were compared for individuals with CFS, FM, and IBS by using logistic regression analyses adjusted for age and sex.
Results: Prevalence rates of CFS, FM, and IBS were 1.3%, 3.0%, and 9.7%, respectively. Individuals with CFS, FM, and IBS had significantly more mood (odds ratios [ORs] = 1.72-5.42) and anxiety disorders (ORs = 1.52-3.96) than did individuals without FSSs, but prevalence rates were low (1.6%-28.6%). Individuals with CFS more often had mood (ORs = 2.00-4.08) and anxiety disorders (ORs = 1.63-2.32) than did individuals with FM and IBS. Major depressive disorder was more common in FM than in IBS (OR = 1.58, 95% confidence interval = 1.24-2.01), whereas these groups did not differ on dysthymia or anxiety disorders.
Conclusions: Mood and anxiety disorders are more prevalent in individuals with FSSs, and particularly CFS, than in individuals without FSSs. However, most individuals with FSSs do not have mood or anxiety disorders.