| The association between atopic disorders and depression: The Northern Finland 1966 Birth Cohort Study | ||
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As reviewed by Galil (2000), associations between asthma and psychiatric symptoms were explained with the help of psychoanalytic theories earlier in the 20th century: it was, for example, suggested that asthma was caused by an excessive dependence on the mother and that it was precipitated by traumatic separations. Ever since genetic factors behind both asthma and depression have become evident, these earlier psychoanalytic explanations have largely been abandoned (Galil 2000).
Higher than normal rates of IgE-mediated allergies have been reported in patients with depression (Nasr et al. 1981, Sugerman et al. 1982). Nasr et al. (1981) evaluated the personal and family history of bronchial asthma and/or allergic rhinitis from 82 psychiatric patients (58 inpatients and 24 psychiatric clinic outpatients). Psychiatric diagnoses were based upon the 3rd edition of the Research Diagnostic Criteria. A semi-structured interview was conducted to explore the relationship between physical and mental problems. The cases of intrinsic asthma were excluded from the analyses since they were not likely to be allergic in nature. A statistically significantly (p < 0.005) higher incidence of atopic disorders was found in affective patients (16/48) than in schizophrenic patients (2/34).
Sugerman et al. (1982) compared IgG, IgA, IgM, IgE, and IgD antibodies in adult alcoholic, depressive, and schizophrenic patients with those of adult, healthy controls. Total above mentioned and specific IgE antibodies were assessed, using 12 inhalant and 21 food allergens. No statistically significant differences were observed in the total immunoglobulin results between patients and controls. However, significant differences were found between the groups for allergen specific-IgE with depressive patients giving the greatest number of positive test results.
Hashiro and Okumura (1997) investigated anxiety (manifest anxiety scale, MAS), depression (self-rating depression scale, SDS), and psychosomatic symptoms (Cornell Medical Index, CMI) in 45 patients with atopic dermatitis and 34 normal controls. On the MAS, the atopic dermatitis group did not show any statistical difference from the normal controls. When compared with the controls, the SDS and the CMI produced statistically significantly higher scores (p < 0.05 and p < 0.01, respectively) in patients with atopic dermatitis. With regard to SDS, 44.4% of the patients with atopic dermatitis had scores of 40 or more (indicating a depressive state including depressive neurosis, but no major depression), the corresponding percentage being 29.4% in the normal controls. After classifying atopic patients in three degrees of severity (mild, moderate and severe), the patients with moderate symptoms were more depressive than the normal controls (p < 0.01). The authors concluded that the patients with atopic dermatitis were more depressive and psychosomatic symptom-prone than the normal control individuals.
In a study conducted by Centanni et al. (2000), the anxiety and depression level was tested with State Trait Anxiety Inventory and ZUNG questionnaires in a population of 80 asthmatic patients. Fourty patients with chronic viral hepatitis B or C, and 40 healthy subjects were recruited as control groups, and, thereafter stratified according to sex, age and education to parallel the asthmatic sample. The results showed that asthmatic patients had statistically significantly higher scores both in State Trait Anxiety Inventory (p < 0.05) and ZUNG (p < 0.05) when compared with controls. In the ZUNG questionnaire, 27 asthmatic patients (33.8%), 10 patients with liver disease (25%) and 5 healthy controls (12.5%) had higher scores than the cut-off point (40 out of 80), indicating higher traits of depression. With regard to both questionnaires, in the asthmatic and healthy populations females had higher scores (p < 0.05 and p < 0.01, respectively) when compared with men, whereas among patients with liver disease, the two subgroups showed no gender difference. The limitation of this study was that allergic and non-allergic asthma was not analyzed separately.
Brown et al. (2000) conducted structured clinical interviews (SCID-IV) on 32 inner city outpatients with moderate to severe asthma to identify current and past psychiatric illnesses. They found that 25% of their study material had current major depressive disorder, but the majority of them (75%) did not receive antidepressants. The investigators called for interventions aimed at identifying and treating psychiatric disorders among asthmatic outpatients.
Further, in a study conducted by Goethe et al. (2001) the prevalence of depressive symptoms was assessed also in a sample of inner-city asthma patients. By using the Center for Epidemiologic Studies Depression Scale, 55% out of 307 asthma patients had scores in excess of the cut-off point for depression (Goethe et al. 2001).
Bell and colleagues (1991) conducted a questionnaire study in a nonclinical sample of 379 college students, examining the possible association between depression and IgE-mediated allergies. Measures included self-reports of the histories of depression and allergic disorders, and specific environmental allergens as well as ratings of affective symptoms of depression (4-point scale). Of the subjects, who had ever received a professional diagnosis of depression (n = 17), 71% also indicated a history of some type of allergic disorder; the difference being statistically significant (p < 0.05) when compared with non-depressive students. The findings were comparable and significant, when the sample was restricted to those with histories of professional allergy diagnoses as well. Furthermore, when the entire sample was divided into four depression groups on the basis of frequency of self-rated current depression (from rarely depressed = 1 to frequently depressed = 4), the most depressed group had a much higher frequency of asthma than did the less depressed group. Thus, the authors suggested that dysfunctions of the immune system could play a role behind the degree of severity of the depression.
Cohen et al. (1998) followed prospectively a cohort of over 700 randomly selected children from early childhood (ages 1–10 years in 1975) to young adulthood in 1992. In 1975, mothers of these children were interviewed to obtain the health status and a range of other factors relevant to the children’s well-being. The follow-up interviews were conducted in 1983, 1985–1986 and 1991–1993. In 1983 and 1986, parent and child interviews were done and the presence of psychiatric disorders was assessed by using a modification of the Diagnostic Interview Schedule for Children. In 1992, only the young adults were investigated in respect of the psychiatric disorders by using an expanded Diagnostic Interview Schedule for Children. Strong positive associations were found between the preceding atopic disorders and a subsequent new-onset of major depressive disorder with the odds ratio reaching even up to 6.41 (95% CI 2.42–16.46) from early childhood to adolescence and still being 1.88 (95% CI 1.07–3.30) from childhood to adulthood.
In a cross-sectional analysis of survey data from 6836 adults between the ages of 20 and 39, Hurwitz and Morgenstern (1999) examined the associations of allergic conditions with depression and low-back pain. A history of depression was obtained from the Diagnostic Interview Schedule. Study subjects responded to questions regarding history of asthma, hay fever and other allergies (i.e., history of insect reaction, food reaction, pet allergy and history of shot/test reaction). The investigators found that respondents with both asthma and hay fever were twice as likely to have been diagnosed with major depression in the past 12 months (OR = 2.06, 95% CI 1.32–3.21 and OR = 2.03, 95% CI 1.28–3.20, respectively) than those without these illnesses. The corresponding odds ratio was 1.87 (95% CI 1.25–2.79) if respondents had a history of any allergy/allergic reaction.
While investigating economic consequences of co-morbid depression, anxiety, and allergic rhinitis in a database of over 600000 privately insured persons, Cuffel et al. (1999) found that allergic rhinitis was associated with increased rates of depression and anxiety disorders, the OR of depressive disorders being approximately 1.7-fold (95% CI 1.63–1.73) in the allergic rhinitis sample when compared with the non-allergic rhinitis sample. In addition, co-morbid allergic rhinitis, depression and anxiety were associated with increased health and mental health expenditures. Interestingly, prescription treatment of allergic rhinitis was found to moderate the increased expenditures associated with co-morbidity (Cuffel et al. 1999).
There are few studies that investigate the presence of atopic disorders in relatives of patients suffering from depression. However, as described in chapter 2.9.1, Nasr et al. (1981) evaluated the personal and family histories of bronchial asthma and/or allergic rhinitis from 82 psychiatric patients. With regard to familiality, they found that the rate of atopy in first-degree relatives of the patients suffering from bipolar and unipolar depression was statistically significantly (p < 0.005) higher than that of the relatives of the schizophrenic patients (13.5% vs. 5.5%). The authors suggested that the high rate of concurrence of atopic disorders and affective illness might be indicative of the existence of a genetic association/a common pathophysiological mechanism between these disorders.
Likewise, there are only a few studies in which the association of depression in family members of an atopic proband has been investigated. In support of the genetic linkage hypothesis it has been, however, noted that mothers of asthmatic children exhibited statistically significantly (p = 0.01) higher rates (45.4%) of depression when compared with controls (27.7%) (Davis 1977). It has been, however, suggested that this link could also have environmental explanations, such as family interactional processes (Wamboldt et al. 1996, 2000, Galil 2000). Wamboldt et al. (1996) found that first degree relatives of adolescents with severe asthma had also statistically significantly (p = 0.003 in male relatives and p < 0.001 in female relatives) higher rates of depression when compared with those of non-ill comparison samples obtained from previously reported studies. This clearly supported the notion of a genetic association between these disorders (Galil 2000).
Twin-studies, based on non-clinical samples, are also suggesting a common genetic rather than an environmental etiology of these two disorders (Wamboldt et al. 1998, 2000). In a community sample of 207 twin pairs (children, whose mean age was 7 years and 7 months) the association between atopy and behavioural symptoms was investigated by using parent report questionnaires. The children’s behaviour was assessed with the help of the Child Behavior Checklist. The atopy score was derived from questioning the parent about whether a doctor had ever said that the child had allergies to pollen, food, or medicines, or whether a doctor diagnosed the child as having asthma or treated the child as a consequence of allergy shots. The results suggested that a common additive genetic effect accounts for 77% of the covariance between atopic symptoms and the symptoms of anxiety or depression (Wamboldt et al. 1998) Recently, Wamboldt et al. (2000) demonstrated the existence of an association between self-reported indices of atopic illness and at least moderate depression, according to the Beck Depression Index (BDI), in a large sample of Finnish adult twins. The authors estimated that 64% of the association between atopy and depression were due to additive genetic effects but, as the authors pointed out themselves, their measures to ascertain allergic status – a tabulation of up to three diagnoses of allergic disorders derived from questionnaire responses – were crude and a single BDI score provided only a very limited approximation of lifetime depression (Wamboldt et al. 2000).
As reviewed by Wamboldt et al. (2000) there exist also certain environmental factors, which could conceivably influence both disorders. Of the family interactional processes, parent-child conflict/parental criticism has been shown to be associated with both asthma and depression (Hermanns et al. 1989, Schobinger et al. 1992, Asarnow et al. 1993, 1994, Wamblodt et al. 2000).
With regard to sociodemographic factors, a prevalence of depression has been shown to be associated with decreasing social class (Lehtinen & Joukamaa 1994). On the other hand, belonging to an unprivileged social class has been noted to be related to lower incidences of allergies (Williams et al. 1994). In previous Finnish surveys, depression has been shown to be most prevalent in the most heavily populated areas of the country, i.e., in southern Finland, and in cities (Väisänen 1975, Lehtinen & Joukamaa 1994). Furthermore, as presented in chapter 2.2, having experienced a farm environment during childhood had been noted to be correlated with lower incidences of allergies (Kilpeläinen et al. 2000). Large numbers of children in a family and mother’s high parity were found to be associated with decreased risks of atopic allergies (Strachan 1989, Pekkanen et al. 2001b), but an increased probability of depressive disorders (Kemppainen et al. 2000).
In previous studies, also exposure to tobacco smoke in utero, and current own smoking activities have been shown to be associated with atopic disorders (Backer et al. 2002, Devereux et al. 2002) and depression (Fergusson et al. 1998, Dierker et al. 2002). However, also opposite results regarding the effect of exposure to tobacco smoke on atopic sensibilization have been published: the prevalences of allergic asthma and allergic rhino-conjunctivitis have been shown to be decreased with increasing exposure to tobacco smoke in an adult Swedish study population (Hjern et al. 2001). In addition, children, who had been exposed to tobacco smoke in childhood, were noted to have lower risks for atopic disorders (Hjern et al. 2001, von Linstow et al. 2002).