This study replicates at 1-year follow-up our earlier finding showing an association between asthma attacks and internalizing disorders among island Puerto Rican children. Children with a lifetime history of asthma attacks had higher odds of having an internalizing disorder at baseline6,18
and at 1-year follow-up than children without asthma attacks, after controlling for sociodemographic measures. Therefore, these data show that comorbidity between asthma attacks and internalizing disorders is a consistent finding across time. However, this study did not show a relationship between asthma attacks and persistence of internalizing disorders. Therefore, the time-course of internalizing disorders may not be different between children with and without asthma attacks.
The longitudinal design of this study extends the literature by showing that the association between asthma attacks and internalizing disorders is a consistent finding in the same population over a 1 year-time period. It is important to examine this relationship longitudinally to determine whether this association exists over time at both the group and individual level. As a group, children with asthma consistently appear to be at greater risk for internalizing disorders. The present study is consistent with many cross-sectional studies showing an association between internalizing symptoms and asthma.13
Previous longitudinal studies have shown that pediatric asthma is associated with elevated risk for development of subsequent behavioral problems later in childhood15
and panic disorder in adulthood.14
These studies suggest that asthma may be a contributing factor to the etiology of internalizing symptoms.
Psychological and biological factors may contribute to the high rate of comorbidity between internalizing disorders and asthma. The ongoing, daily stressors involved in asthma management, such as trigger avoidance and medication regimens, may increase psychological symptoms among children. Also, cognitive variables associated with reactions to asthma, such as fear of bodily sensations29
and learned helplessness,30
may contribute to anxiety and depression, respectively. Mowrer’s two-factor theory of classical and operant conditioning31
may also be applied to this relationship. For example, a child who has experienced repeated asthma attacks at social events might start avoiding parties because of embarrassment, which is then maintained via operant conditioning (i.e., negative reinforcement). Conversely, stress may contribute to greater asthma morbidity via autonomic32–33
pathways involved in stress responses. Behavioral factors, such as poor adherence with asthma self-management plans, may also play a role in poor asthma control.37
These pathways may then lead to a cycle of asthma exacerbation and further stress, depression and/or anxiety among children with internalizing disorders.
The findings from the present study do not support the notion that asthma attacks are associated with persistence of internalizing disorders across a 1-year time period. The interaction between asthma attacks and internalizing disorders at Wave 1 was not significant in predicting an internalizing disorder at Wave 2. Therefore, the association found at 1-year follow-up may reflect the combination of higher baseline prevalence rates of internalizing disorders and the natural time course of internalizing disorders among youths. Both groups displayed a similar rate of attenuation for internalizing disorders. One explanation for these findings is that asthma and internalizing disorders may simply be two chronic, coexisting conditions that do not reciprocally influence one another. Previous studies have demonstrated the continuity of internalizing disorders across time among youths in the community38
and in primary care.39
Costello and colleagues38
found that children with a previous depressive episode were 7.0 times more likely to experience a later depressive episode. Children with a previous diagnosis of an anxiety disorder were 2.4 times more likely to meet criteria for a later diagnosis of an anxiety disorder. Indeed, longitudinal studies have shown that the strongest predictor of psychopathology at Wave 2 is psychopathology at Wave 1,40
which was also found in the present study.
The continuity of depression and anxiety may explain why the association between asthma and internalizing disorders is seen over time, independent of any unique relationship between these two conditions. Rates of relapse and persistence of internalizing disorders may not be different between children with and without asthma. In the present study, 31% of children with asthma attacks and 24% of children without asthma attacks had an internalizing disorder at both waves of the study. It will be important to explore whether similar patterns of persistence and remission are found over longer periods of follow-up. Although the course of internalizing disorders may not be different between children with and without asthma, these findings show that children with asthma attacks are consistently at greater risk for having an internalizing disorder.
These conclusions should be interpreted with caution because of several limitations in the present study. Our measure of asthma was simply based on parent report of asthma attacks and not confirmed by medical chart review or physician assessment using current national guidelines.41
We also did not have information on asthma severity, which may be a key factor in the relationship between asthma and persistence of internalizing disorders. In addition, the assessment of asthma attack was based on lifetime history, although the assessment of psychiatric disorders was based on the past 12 months. Therefore, it was not possible to examine whether internalizing disorders preceded the development of asthma. Examining the etiology of the relationship between asthma and internalizing disorders was also limited by lack of information regarding the age at asthma onset. Finally, the small number of children who met criteria for an internalizing disorder atWave 2 limited our ability to examine anxiety and depressive disorders separately. Nevertheless, the high retention rate of participants (94.9%) at 1-year follow-up suggests that this community sample was a representative one.