We recently published a study using the CBCL, CDI, and CDRS-R to identify the prevalence of depressive symptoms in asthmatic children from a primarily inner-city population (74% with moderate to severe asthma) and assess the correlation of these symptoms with asthma severity.20 Given the potential confound of parent mood, we also assessed depression in parents using the Beck Depression Inventory (BDI). The unique aspects of this study were the use of depression scales from 3 different raters (parent, child, and clinician); the use of the CDRS-R in an asthmatic sample; and defining asthma severity based on National Heart, Lung, and Blood Institute criteria, which integrate parent and child reports of asthma symptoms with forced expiratory volume in 1 second (FEV1) scores. It was hypothesized that there would be an elevated rate of depressive symptoms, with the CDRS-R score producing the best correlation with asthma severity, since it integrates parent and child reports with direct clinical observation.
One quarter of the 129 children scored in the clinical range (defined as a T-score of greater than 65 for all scales to equilibrate findings across measures) on any single depression scale (21% on the CBCL, 5% on the CDI, and 6% on the CDRS-R), but only 3% scored in the clinical range on all measures. Of the patients identified as depressed on at least 1 scale, 30% scored in the clinical range on 2 scales, with the best agreement between CDRS-R and CDI (21%) and between CBCL and CDRS-R (21%). Compared with standardized norms, mean scores for the sample were elevated on the CDRS-R (32) and CBCL (T-score of 58 on the internalizing subscale) but not on the CDI (8.5). Hence, there was an elevated rate of depressive symptoms that were primarily driven by parent report.
Among the mothers, 43% scored in the depression range with a mean score of 11.3, which is above the standard cutoff for depression (10). Correlation between informants was low. Interestingly, the CDRS-R did not identify more depressed patients than did the CDI, and the 2 scales largely identified different patients as depressed. Most identified cases of depression have not yet been clinically confirmed, which allows for the determination of which scale is the optimal tool for evaluating depression in children with asthma.
Surprisingly, the CDI score was most strongly correlated with asthma severity (r = .25; P < .01). While the effect size was small (6% to 7% of the variance in asthma severity was attributable to CDI score), it was consistent with the results of other studies examining the effects of psychological variables on asthma severity.12,13 The CDRS-R failed to correlate with asthma severity even after controlling for age, sex, and parent depression. Because asthma severity was defined by integrating objective medical indices with child and parent reports, it is unlikely that these correlations were inflated by reporter bias from a somatically oriented informant (ie, a parent or child who reports elevated mood symptoms is more likely to report asthma symptoms).
Nonetheless, because of the high rates of parent depression and the correlation between parent and child depressive symptoms (r = .20; P < .05), the effect of maternal depression was factored out to remove any potential bias of mood on parent reporting. There was no significant change in the associations between asthma severity and any of the parent-reported depression measures after factoring out maternal depression.Roots of comorbidity
Miller and Wood5 found that inducing feelings of sadness and despair in a laboratory setting produced changes in oxygen saturation that were consistent with airway constriction. In nonpsychiatric samples, children are more likely to report depressive thoughts or feelings, while parents are more likely to report behavior changes.19 A recent factor analysis of the CDRS-R also found limited correlation between clinician ratings of observed affect and a child's report of his internal mood state.14 These findings suggest that observable signs of depression, such as changes in sleep, appetite, or frustration tolerance, may not be directly related to physiologic parameters relevant to asthma. Self-report forms may more accurately capture the depressive symptoms that are physiologically germane to asthma, such as internal mood state, which should be the target of depression treatments in children with asthma.
The cross-sectional nature of these findings does not allow for a determination of the causal pathways between depression and asthma. While it seems likely that the interaction is bidirectional, it is unknown whether depression primarily drives asthma severity or the reverse. Psychosocial adversity or treatment adherence could also explain the association between depression and asthma severity. However, the specific connection between self-reported depressive symptoms and asthma severity that was unaffected by parent mood is suggestive of a direct link between the two. We are currently running a laboratory protocol to identify the pathways and mechanisms by which depressed mood produces airway compromise in asthma.
These findings suggest that treatment of depression may improve asthma outcomes in comorbidly ill children. We are in the process of designing an intervention trial for depressed adolescents with asthma to further evaluate this possibility.
Our group provides clinical treatment to a large number of children with asthma and psychiatric illnesses and has found that depression can be safely and effectively treated in the presence of asthma. There are few drug-drug interactions between the SSRIs and asthma medications, although paroxetine(Drug information on paroxetine) and fluoxetine(Drug information on fluoxetine) should be used cautiously with other drugs that are metabolized through the cytochrome P-450 2D6 hepatic pathways. ß-Blockers are contradicted in patients with asthma and oral steroids may exacerbate mood symptoms in children with preexisting psychiatric illness, necessitating careful monitoring when prescribed. As with any child or adolescent, FDA warnings regarding the use of antidepressants in children younger than 18 years should be reviewed with the family before prescribing, and careful monitoring for adverse emotional reactions is recommended.Conclusion
There is an elevated rate of depression in children and adults with asthma that appears to be associated with worsening asthma severity. Self-reported depressive symptoms may be of particular concern in asthmatic children. Therefore, any attempt to assess depression should include a direct interview with the child, and the CDI appears to be a useful tool for this purpose. While there are few data on the treatment of depression in children who have asthma, clinical experience suggests that in most cases they may be safely and effectively treated with existing depression treatments, including SSRIs. While initial reports are encouraging, controlled studies are needed to see whether improvement in mood leads to enhanced medical outcomes.