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ORIGINAL ARTICLES |
From the Department of Psychiatry, Columbia University, New York, New York.
Address correspondence and reprint requests to Ramin Mojtabai, MD, 10 Waterside Plaza, Apt. 5J, New York, NY 10010. E-mail: rm322{at}columbia.edu
| ABSTRACT |
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Methods: In a sample of 9,240 parentchild dyads drawn from the 1999 US National Health Interview Survey, the association of childhood atopic disorders with parental major depression, generalized anxiety disorder, and panic attacks was examined. Parental DSM-IV psychiatric diagnoses were ascertained by the Composite International Diagnostic Interview, Short-Form (CIDI-SF).
Results: Parental major depression and panic attacks were associated with childhood atopic disorders only in biological parentchild dyads (adjusted odds ratios = 1.67 for major depression and 1.46 for panic attacks), and among these more strongly in motherchild dyads. Parental atopic disorders and parental psychopathology had an additive effect on the risk of atopic disorders in the offspring.
Conclusion: Findings from this study lend support to the "shared genetic liability" hypothesis for the association of childhood atopic disorders and parental major depression and panic attacks.
Key Words: atopic disorders major depression panic attacks
Abbreviations: NHIS = National Health Interview Survey; CIDI-SF = Composite International Diagnostic Interview, Short Form; DSM-IV = Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition; MD = major depression; GAD = generalized anxiety disorder; PA = panic attacks.
| INTRODUCTION |
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The present study further explores the link between parental psychopathology and childhood atopic disorders in a large sample of biological and nonbiological parentchild dyads drawn from the general population. The study also tests Timonen and colleagues (15) maternal inheritance hypothesis by examining whether the link between parental psychopathology and childhood atopic disorders is limited to motherchild dyads or is found in fatherchild dyads as well.
| METHODS |
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From each family in the NHIS, one sample adult and one sample child (if the family has a child) are randomly selected for more detailed interviews. Information for the sample child is obtained from a knowledgeable adult residing in the household, who is often a parent. The analyses in this paper use the intersection of the sample adult and sample child interviews in which the sample adult was a biological or adoptive/step parent of the sample child.
Main Variables
Parental psychopathology was assessed by Composite International Diagnostic Interview (CIDI) Short Form (CIDI-SF). The CIDI-SF is a structured diagnostic interview designed for use by trained nonclinician interviewers. The CIDI-SF was derived from the longer and more detailed Composite International Diagnostic Interview (28), and was revised to screen for disorders defined in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (29). In the 1999 NHIS, the CIDI-SF modules for three 12-month diagnoses were used: major depression, generalized anxiety disorder, and panic attacks.
Childhood atopic disorders were assessed by a set of questions asking if the child had had "hay fever," "respiratory allergies," "eczema or skin allergies," "wheeze or whistling sound in the chest," or "food allergies" in the past 12 months or had been diagnosed by a health professional as having asthma. For this report, a childhood atopic disorder was defined by the presence of any of these indicators.
It may be argued that "wheeze or whistling sound in the chest" is not as specific an indicator for atopic disorders as the other reported symptoms. However, it is noteworthy that 75.4% of the children with this symptom also had at least one of the other symptoms. Furthermore, there is some evidence that mild wheezing might be an indicator of a less severe forms of atopic disorder that is not diagnosed as such (3). Finally, further analysis after excluding this symptom produced results similar to those presented here.
Control Variables
Atopic disorders in adults were assessed by three questions about being diagnosed by a health professional with asthma or hay fever or having had a "wheezing or whistling sound in the chest" in the past 12 months. For this report, an adult atopic disorder was defined by the presence of any of these indicators. Similar to the case of children, 56.0% of the participants who reported "wheezing or whistling sound in the chest" also reported being diagnosed with asthma or hay fever. Further analyses after excluding this symptom produced results similar to those presented here.
Sociodemographic characteristics included the interviewed parents age, gender, race, parental smoking (number of cigarettes smoked per day), family size, family income, and the childs gender and age.
Analyses
Analyses were conducted in two stages. First, the association of parental psychopathology with childhood atopic disorders was examined using a multiple logistic regression model in which the dichotomous variable of childhood atopic disorders was the outcome variable of interest and major depression, generalized anxiety disorder, and panic attacks were the independent variables of interest. Analyses adjusted for the control variables described above. In addition to statistical tests for the regression coefficients, Wald tests for the overall effects of psychopathology were also conducted. A statistically significant regression coefficient or overall Wald test for psychopathology among biological parents but not among nonbiological parents would lend support to the shared genetic liability hypothesis.
Second, the impact of the parents gender on the association of parental psychopathology and childhood atopic disorders was examined by running separate regressions for motherchild and fatherchild dyads similar to the one described above. These analyses were limited to biological parentchild dyads and parental mental health conditions found to be significantly related to childhood atopic disorders in the first stage of the analyses. Analyses adjusted for the control variables described above. A statistically significant regression coefficient or overall Wald test for maternal psychopathology, but not paternal psychopathology, would lend support to the maternal inheritance hypothesis.
The logistic regression models were fitted by the svylogit routine of STATA 8.0 (StataCorp., College Station, TX) statistical program, which accommodates complex survey data by taking survey weights and design elements into account. P < .05 was considered statistically significant.
| RESULTS |
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The average age of parents was 36.7 years (SD = 8.3); 64.9% (N = 6,000) were female and 35.1% (N = 3,240) male; 58.6% (N = 5,411) were non-Hispanic white, 23.2% (N = 2,144) Hispanic, 14.8% (N = 1,370) non-Hispanic black, and 3.4% (N = 315) from other racial/ethnic groups. Major depression was the most common of the three psychiatric disorders ascertained, affecting 6.3% (N = 584) parents followed by panic attacks, affecting 3.3% (N = 309) and generalized anxiety disorder, affecting 3.2% (N = 292). Adult atopic disorders were more common, affecting 18.9% (N = 1,742).
The median size of the families from which the parentchild dyads were drawn was four members. The average income of 22.2% (N = 2,053) of the families was less than $20,000 per year.
In the multiple logistic regression analyses, parental major depression and panic attacks were associated with childhood atopic disorders at a statistically significant level only in biological parent-child dyads (Table 1). Parental atopic disorders, however, were associated with childhood atopic disorders both in biological and nonbiological parentchild dyads (Table 1). In biological parentchild dyads, the likelihood of childhood atopic disorders was lower in children of Hispanic parents, children who came from larger families and had lower income. Boys and older children had an increased risk of atopic disorders (Table 1).
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In the multiple logistic regression analyses limited to biological parentchild dyads, major depression and panic attacks in mothers, but not fathers, were associated with childhood atopic disorders at a statistically significant level (Table 2). No such gender differences were observed in the association of parental and childhood atopic disorders (Table 2).
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Further analyses, using adjusted probabilities obtained from the logistic regression models, indicated that parental atopic disorders and parental mental health conditions had additive effects on the risk of atopic disorders in children (Figure 1). Among parents who had atopic disorders but no major depression or panic attacks, atopic disorders were observed in 47.7% of the offspring. Among parents who had major depression or panic attacks but no comorbid atopic disorders, atopic disorders were observed in 36.7% and 36.0% of the offspring, respectively, whereas among parents with both atopic disorders and major depression and/or panic attacks, atopic disorders were observed in 63.0% of the offspringconsiderably higher than either of the other groups (Figure 1) and 2.5 times higher than the group whose parents had neither condition (prevalence = 25.1%).
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| DISCUSSION |
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This study also had several strengths that complement and extend findings from previous studies that were mostly based on small clinical samples, including a well-characterized, large, and representative population sample, structured interviews for mental disorders, and availability of both biological and nonbiological parentchild dyads. In the context of these strengths and limitations, data from this study provide further support for the role of parental mental health in childhood atopic disorders. The association appears to be specific to two of the mental health conditions covered in the study, i.e., major depression and panic attacks. This finding is consistent with past research suggesting an association between childhood atopic disorders and parental panic disorder (1,6). However, to our knowledge these data are the first general population data that indicate a similar relationship between childhood atopic disorders and parental major depression, ascertained by a structured interview instrument and according to DSM-IV criteria.
Furthermore, the observation that the association of parental psychopathology and childhood atopic disorders is limited to biological parentchild dyads is consistent with the hypothesis that a shared genetic liability underlies the intergenerational association of these conditions (1,15). It is interesting to note that although the relationship of parental mental health conditions and childhood atopic disorders was fully dependent on the biological relationship of parentchild dyads, the relationship of parental atopic disorder with childhood atopic disorder was only partially dependent on the biological relationship. This finding may suggest that the relationship of parental and childhood atopic disorders is, in part, mediated by current environmental factors such as household exposure to allergens that are shared by all parentchild dyads, whereas the relationship of parental mental health conditions and childhood atopic disorders is not mediated by such common environmental exposures. This possibility needs to be tested in future parentchild studies.
It is also noteworthy that parental major depression and panic attacks confer additional risk of atopic disorders in offspring, beyond that of parental atopic disorders (Figure 1). This finding is consistent with past research, which noted that parents with both mental health conditions and atopic disorders are at increased risk of atopic disorders compared with children of parents with atopic disorders alone (7,9).
Although the nature of the shared genetic liability remains unknown, it is noteworthy that the association is more pronounced in motherchild than in fatherchild dyads. This finding is consistent with the maternal inheritance hypothesis proposed by Timonen and colleagues for explaining the association of maternal atopic disorders and depression in the offspring (15). These authors suggest that this pattern of inheritance may reflect mitochondrial inheritance. Mutations in mitochondrial DNA have been reported both in atopic and other skin disorders (31) and in bipolar mood disorder (32). The other potential explanation for this pattern of inheritance put forth by Timonen and colleagues is genomic imprinting (33) in which the same gene would have a different effect, depending on its maternal or paternal origin. A competing explanation for the motherchild genetic transmission of liability is fetal exposure. However, an increased risk of mood disorders in offspring of mothers with atopic disorders has also been observed (15). Although shared genetic liability appears to be a parsimonious explanation for the reciprocal transgenerational association of mental health and atopic disorders, other potential explanations such as the mediating role of childhood psychopathology or direct impact of adult psychopathology in the perinatal period merit further exploration (34). As Simonof notes (34), distinguishing between these competing models is often difficult and requires additional information from other sources. A more definitive answer may emerge only from triangulation of evidence from a number of different approaches.
| NOTES |
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Received for publication June 22, 2004; revision received November 23, 2004.
DOI:10.1097/01.psy.0000160460.59505.db
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