Functional somatic disorder (FSD) is a unifying diagnosis that includes functional somatic syndromes such as irritable bowel, chronic widespread pain (CWP) and chronic fatigue. Several psychological factors are associated with FSD. However, longitudinal population-based studies elucidating the causal relationship are scarce.

To explore if neuroticism, perceived stress, adverse life events (ALEs) and self-efficacy can predict the development of FSD over a 5-year period.

A total of 4288 individuals who participated in the DanFunD baseline and 5-year follow-up investigations were included. FSD was established at both baseline and follow-up, with symptom questionnaires and diagnostic interviews. Neuroticism was measured with the short-form NEO Personality Inventory, perceived stress with the Cohen's Perceived Stress Scale, ALEs with the Danish version of the Cumulative Lifetime Adversity Measure and self-efficacy with the General Self-Efficacy Scale. Associations were investigated with multiple logistic regression models.

Perceived stress predicted incident FSD, irritable bowel, CWP and chronic fatigue (odds ratios: 1.04–1.17). Neuroticism predicted incident FSD and chronic fatigue (odds ratios: 1.03–1.16). ALEs predicted incident FSD, CWP and chronic fatigue (odds ratios: 1.06–1.18). An increase in perceived stress from baseline to follow-up was associated with incident FSD, irritable bowel, CWP and chronic fatigue (odds ratios: 1.05–1.22). Contrary, an increase in self-efficacy seemed to be a protective factor (odds ratios: 0.89–0.99).

High neuroticism, high perceived stress and a high number of ALEs are risk factors for the development of FSD. Particularly perceived stress seems to be an important contributor to the onset of FSD.

Psychological treatment for functional somatic syndromes (FSS) has been found moderately effective. Information on how much treatment is needed to obtain improvement is sparse. We assessed the efficacy of a brief and extended version of group-based Acceptance and Commitment Therapy (ACT) v. enhanced care (EC) for patients with multiple FSS operationalised as Bodily Distress Syndrome multi-organ type.

In a randomised controlled three-armed trial, consecutively referred patients aged 20–50 with multiple FSS were randomly assigned to either (1) EC; (2) Brief ACT: EC plus 1-day workshop and one individual consultation; or (3) Extended ACT: EC plus nine 3-h group-based sessions. Primary outcome was patient-rated overall health improvement on the five-point clinical global improvement scale 14 months after randomisation. A proportional odds model was used for the analyses.

A total of 180 patients were randomised; 60 to EC, 61 to Brief ACT, and 59 to Extended ACT. Improvement on the primary outcome after Extended ACT was significantly greater than after EC with an unadjusted OR of 2.9 [95% CI (1.4–6.2), p = 0.006]. No significant differences were found between Brief ACT and EC. Of the 18 secondary outcomes, the only significant difference found was for physical functioning in the comparison of Extended ACT with EC.

Patients rated their overall health status as more improved after Extensive ACT than after EC; however, clinically relevant secondary outcome measures did not support this finding. Discrepancies between primary and secondary outcomes in this trial are discussed.

Many specialty-specific functional somatic syndrome diagnoses exist to describe people who are experiencing so-called medically unexplained symptoms. Although cognitive–behavioural therapy can be effective in the management of such syndromes, it is rarely available. A cognitive–behavioural therapy suitable for group treatment of people with different functional somatic syndromes could address this problem.

To test the efficacy of a cognitive–behavioural therapy (Specialised Treatment for Severe Bodily Distress Syndromes, STreSS) designed for patients with a range of severe functional somatic syndromes.

A randomised controlled trial (clinicaltrials.gov, NCT00132197) compared STreSS (nine 3.5 h sessions over 4 months, n = 54) with enhanced usual care (management by primary care physician or medical specialist, n = 66). The primary outcome was improvement in aggregate score on subscales of the 36-item Short Form Health Survey (physical functioning, bodily pain and vitality) at 16 months.

Participants receiving STreSS had a greater improvement on the primary outcome (adjusted mean difference 4.0, 95% CI 1.4–6.6, P = 0.002) and on most secondary outcomes.

In the management of functional somatic syndromes, a cognitive–behavioural group treatment was more effective than enhanced usual care.

This study explores the incidence and nature of mental illness among persistent somatisers, and analyses their use of mental health services.

Individuals with at least ten admissions to non-psychiatric departments during an 8-year period were studied. Persistent somatisers (n = 56) were compared with other frequent users (n = 57) of non-psychiatric services.

Of the persistent somatisers, 82% had been examined by a psychiatrist at least once (median, 3 times). Sixteen per cent were mentally retarded, 48% were dependent on alcohol or drugs, and 48% had DSM–III–R personality disorder. The most prevalent ICD–10 diagnoses were anxiety states (54%), depressions (30%), phobias (18%) and psychoses (20%).

Persistent somatisation is associated with severe mental illness and a broad spectrum of heterogeneous psychiatric diagnoses and syndromes. Persistent somatisers impose a serious burden on the mental health care system.