Psychiatric–Medical ComorbidityAnxiety and depression in patients with self-reported food hypersensitivity☆
Introduction
Self-reported food hypersensitivity (SFH) is common. In several Western countries, up to 20% of the general population claim adverse reactions to food [1]. However, the discrepancy between suspected and confirmed food hypersensitivity is considerable. According to current criteria, the term “food hypersensitivity” embraces IgE-mediated and non–IgE-mediated food allergy, as well as nonallergic reactions [2]. Common for most reactions is that the double-blind placebo-controlled food challenge (DBPCFC) is regarded as the “gold standard” diagnostic method [3], but only 1–2% are diagnosed with food allergy when this method is used [4], [5]. In most cases, self-reported reactions to food remain unexplained.
Patients who attribute their symptoms to food hypersensitivity are often severely bothered and experience considerably impaired quality of life [6]. Their complaints are characterized by abdominal discomfort and pain, bloating and altered bowel functions, and patients commonly get a diagnosis of a functional gastrointestinal disorder, most often irritable bowel syndrome (IBS) [7]. In addition, they also often present with extra-intestinal symptoms such as headache, fatigue and musculoskeletal pain [8]. The coexistence of so many diverse unexplained health complaints suggests that the pathogenetic mechanisms are multifactorial and not confined to peripheral hypersensitivity reactions solely [9].
Emotional disturbances may play a role in the pathogenesis of SFH. Patients with psychiatric disorders such as anxiety and depression often present with somatic rather than emotional symptoms, a fact that often contributes to low recognition of these disorders in primary care [10], [11]. It might therefore be hypothesized that for some of the patients who present with somatic symptoms self-attributed to food hypersensitivity, the complaints could be an expression of emotional problems like anxiety and depressive disorders [12]. Bodily symptoms of anxiety and depression may also be misinterpreted as allergic symptoms. Autonomic symptoms such as hyperventilation, sweating and heart palpitations frequently occur in anxiety disorders as well as in allergic and anaphylactoid reactions [13].
There are few studies of psychological factors in SFH [14]. Most of them are based on self-rating questionnaires, from which psychiatric diagnoses cannot be made, and the results are somewhat conflicting. One study reports that SFH is associated with neuroticism and general psychological distress [15]. Higher scores for anxiety, depression, shyness and defensiveness have also been reported [16], [17], while others have not found an association between SFH and psychological problems [18], [19].
To our knowledge, psychiatric interviews have been used in only two studies of patients referred to hospital because of unexplained SFH [20], [21], [22]. Both studies were based on semistructured interviews. Pearson et al. [20], [21] found that 18 of 19 patients had a psychiatric disorder, of which “depressive neurosis” was most common. Limitations of this study were a small patient sample and that the clinical investigations were limited to allergological and dietary assessments. Gastroenterological examinations were not performed. Vatn et al. [22] found that all of their patients fulfilled the diagnostic criteria of undifferentiated somatoform disorders, 24% were depressed and the majority reported current life stress or childhood trauma. These patients were well characterized in terms of allergological, dietary and gastroenterological assessment. However, the patient sample here was also small (n=17).
The main aim of the present study was to assess the prevalence of anxiety and depression in patients with gastrointestinal complaints self-attributed to food hypersensitivity who were also thoroughly examined with respect to allergological, gastroenterological and dietary factors. For this purpose, we wanted to use both self-rating scales and a structured psychiatric interview which is validated according to current diagnostic standards. We also wanted to assess self-rated general psychological distress, as well as neuroticism, which is suggested to be a vulnerability factor for the development of both anxiety and depression [23]. We hypothesized that anxiety, depression, general psychological distress and neuroticism would be more prevalent in patients than in a population-based control group.
Section snippets
Participants
Patients referred by general practitioners or specialist doctors to the Section for Clinical Allergology, Department for Occupational Medicine at Haukeland University Hospital (Bergen, Norway), because of gastrointestinal complaints self-attributed to food hypersensitivity, were considered eligible for inclusion in the study. Pregnant and lactating women were excluded, as well as patients with confirmed inflammatory bowel disease.
The patients went through a comprehensive clinical investigation
Sample characteristics
A total of 178 consecutive patients were considered eligible for the study. Two patients were excluded because of pregnancy, two because of Crohn's disease and 14 because of weak or no gastrointestinal complaints. Thirty patients dropped out because they found the investigation program too extensive or bothersome. The final number of patients included was 130 (107 women/23 men, 82.3%/17.7%), with mean age of 39.5 years (range 18–80 years).
Thirty (28.5%) of the 105 volunteers who were eligible
Discussion
In the present setting of an allergy clinic, anxiety and depression were commonly associated with IBS-like symptoms self-attributed to food hypersensitivity. According to the interviews, the prevalence of any psychiatric disorder was 57%, of which anxiety disorders and depression predominated. According to the questionnaires, levels of anxiety, neuroticism and general psychological distress were significantly higher in patients than in healthy controls. However, we observed some significant
Acknowledgments
We thank the other members of the interdisciplinary MAI investigation group at Haukeland University Hospital for skilful assistance in data collection, and for many fruitful discussions.
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This work was supported by research grants from the Western Norway Regional Health Authority.