The estimated prevalence of SED among children and adolescents exposed to Hurricane Katrina decreased significantly from 15.1% at our baseline assessment 18-27 months after the storm to 11.5% at our assessment 12-18 months later. This reduction is not surprising given that the prevalence of youth mental health problems following natural disasters tends to decrease over time.6, 17
However, the prevalence of SED among youths exposed to Katrina continues to be considerably greater than the pre-hurricane prevalence of 4.2% estimated in the NHIS using the same measure as the current study.15
Moreover, approximately 8% of youths were estimated to have SED that is directly attributable to the hurricane, indicating that seriously impairing mental health problems resulting from the disaster remain elevated three years after the hurricane. These findings are consistent with those of school-based surveys documenting decreases in psychological problems over time in youths exposed to Katrina, but high levels of ongoing symptomatology.13, 24
Closer examination of the trends in SED shows that approximately two-thirds of children and adolescents with SED at our baseline assessment had recovered by the follow-up. This recovery is offset, though, by a high rate of new SED onsets during the follow-up period. More than half of SED cases at the follow-up did not have SED at baseline. Although these new cases may represent delayed-onset mental health problems related to the hurricane or may simply reflect a normal ebb and flow of SED onsets and offsets that are unrelated to Katrina, the former interpretation is more consistent with the data in light of the fact that we observed a substantially higher number of onsets of H-SED than NH-SED. Furthermore, disaggregation of the trends in SED according to level of stress exposure showed that H-SED onsets were concentrated among youths with high levels of stress, whereas onsets of NH-SED were unrelated to stress exposure. Together, these patterns suggest that new onsets of H-SED are likely delayed reactions to the hurricane. NH-SED onsets, in contrast, probably reflect normal changes of cases in the population. Although similarly high levels of delayed-onset youth mental health problems several years post-disaster have not been reported previously, exposure to ongoing stressors or traumatic events is associated with delayed onset of adult PTSD following disasters.25
Consistent with this finding, a considerable number of delayed-onset mental health problems were observed among adults exposed to Hurricane Katrina.26
This high rate of delayed-onset mental health problems in children and adults may be attributable to the high levels of ongoing stress, exposure to traumatic events, and community disruption that have persisted in Gulf Coast areas due to the slow pace of recovery.10
We found that disaster-related stress exposure was common and associated strongly with SED prevalence and persistence. After accounting for ongoing stress, hurricane-related stressors were associated with SED prevalence at both baseline and the follow-up. Although the associations of these stressors with H-SED were stronger than with NH-SED, the associations with NH-SED were nonetheless significant. In models that control for baseline SED, however, we found that hurricane-related stressors were associated with greater persistence of H-SED but not NH-SED. On one hand, these findings are not surprising, as exposure to disaster-related stressors is consistently identified as a predictor of child psychopathology in previous research,6-9
and was associated specifically with the persistence of PTSD symptoms among children exposed to Hurricane Andrew.6
However, with one exception6
these studies were cross-sectional and did not control for ongoing stress. Evidence from longitudinal studies of adults, on the other hand, indicates that disaster-related traumatic events are not associated with the course of PTSD after accounting for ongoing stressors.18, 25, 27
It is possible that the disaster-related stressors associated with Hurricane Katrina were more severe than those in previous disasters or more highly co-occurring, given that more than one-third of youths in our sample were exposed to three or more hurricane-related stressors,11
thus resulting in a more enduring effect of these stressors on the course of child mental health problems following the hurricane. Children and adolescents with the highest exposure to hurricane-related stressors in our sample were also more likely to experience ongoing stress: of the youths with five or more hurricane-related stressors, more than half continued to have moderate to high ongoing stress at the follow-up. This is unsurprising as families living in the areas that were most devastated by the hurricane experienced higher rates of forced relocation after the storm, housing instability, ongoing disruption and lack of access to services, and dissolution of support networks in their communities.10
Although rarely examined in longitudinal studies of children following natural disasters, the evidence regarding ongoing stress and child mental health has thus far been mixed with some studies reporting an association between post-disaster stressors and psychopathology persistence6, 24
and others reporting no association after accounting for disaster-related stress exposure.28
Among adults, ongoing stress predicts greater persistence and delayed onset of PTSD following disasters.18, 25, 27
Here, we found significant associations between ongoing stress and SED at the baseline and follow-up interviews, as well as with SED persistence after controlling for hurricane-related stressors. Ongoing stress associated with the hurricane has not subsided for many families due to the slow pace of community rebuilding in the Gulf Coast, and this lack of improvement may explain, in part, the continued elevations in youth mental health problems.
Unlike stressors, socio-demographic factors were largely unrelated to SED prevalence or persistence in children exposed to Hurricane Katrina, mirroring findings from our previous cross-sectional report.11
These findings contrast with evidence from previous natural disasters3, 7, 16
and from school-based surveys of youths exposed to Katrina13, 24
documenting higher rates of internalizing symptoms in females and in younger children. The lack of socio-demographic variation in our sample may have resulted from our examination of a wider range of mental health problems, including both internalizing and externalizing pathology. Alternatively, it may reflect that Hurricane Katrina was a disaster that impacted virtually all segments of society due to the depth and breadth of the devastation it caused.
Children and adolescents who experienced decrements in functioning prior to the hurricane were more likely to have persistent SED than children without such difficulties. However, this effect was observed only among youths who experienced low to moderate stress during and after the hurricane. Youths exposed to the highest levels of stress exhibited markedly elevated rates of SED, and more than one-third of these children continued to have SED at the follow-up. The lack of association between pre-hurricane functioning and SED persistence in this group suggests that the magnitude of stress to which these youths were exposed was sufficient to overwhelm the coping resources of many children, regardless of their pre-hurricane functioning. These findings are consistent with previous research documenting strong associations between cumulative stressors and child mental health problems,29-32
as well as with evidence suggesting that once children have been exposed to a high enough number of stressors, the prevalence of psychopathology increases dramatically.31
Importantly, these results validate intuitive efforts that target mental health services to youths who experienced the highest levels of exposure to disaster-related trauma and ongoing stressors.
Our findings indicate that mental health problems among children and adolescents exposed to Hurricane Katrina have decreased over time but remain elevated three years post-disaster. Because SED is a marker of mental health problems that are severe enough to warrant treatment, our findings suggest a continued high level of need for treatment resources among hurricane-exposed children, particularly among youths exposed to high levels of stress. Although marked decreases in the availability of mental health treatment resources occurred following Hurricane Katrina,33, 34
recent efforts to identify children experiencing psychiatric impairment and to provide treatment within schools and existing service structures in hurricane-affected areas hold promise for addressing the ongoing mental health needs of hurricane-exposed youths.35
The above findings should be interpreted in light of study limitations. First, SED was estimated using a screening scale rather than a diagnostic interview. The SDQ has been previously validated and used in national epidemiologic surveys,36
and demonstrated good psychometric properties in estimating SED based on diagnostic interviews in a clinical reappraisal study.23
Nevertheless, screening scales are less precise than clinical interviews, resulting in potential misclassification. Because misclassification was likely non-differential, any imprecision would have resulted in attenuation of the associations between risk factors and SED. Because the SDQ did not include specific questions about PTSD symptoms, our estimates of SED prevalence are most likely conservative. Second, the low response rate to the CAG survey and the exclusion of individuals who were unreachable by telephone probably resulted in under-representation of individuals with high levels of stress exposure and mental health problems, most likely resulting in conservative estimates of the prevalence of SED. Third, we did not assess pre-hurricane SED and parent’s determinations of whether their child’s emotional and behavioral problems were attributable to the hurricane were subjective and susceptible to bias. Parents who experienced high levels of stress during the hurricane may have been more likely to report that their children’s problems were hurricane-related, leading to an overestimation of the association between stress exposure and SED. Although the estimated prevalence of NH-SED is similar to the prevalence of SED reported in the NHIS15
and hurricane-related stressors were more consistently associated with H-SED than NH-SED, some associations between hurricane-related stressors and NH-SED were significant, suggesting some degree of misclassification in parents’ determinations of whether their child’s problems resulted from the hurricane. Fourth, we did not directly interview youths to determine the prevalence of emotional and behavioral problems from the child’s perspective and to estimate parent-child agreement. This may have resulted in underestimates of SED prevalence, as some studies have reported low parent-child agreement on screening measures with parents tending to report fewer severe symptoms than children.37
In subsequent waves of data collection, however, we interviewed a small number of adolescent respondents from the current sample, and these interviews revealed good concordance between adolescent and parent reports of SED using the SDQ. Fifth, due to sample size constraints, we were unable to distinguish persistent cases from new onsets in prediction models examining changes in SED. The extent to which disaster-related and ongoing stressors are differentially associated with persistent and delayed onset child mental health problems remains an important question for future research.
Despite these limitations, the results are quite clear in showing that the prevalence of SED among youths who lived through Hurricane Katrina continues to be substantially elevated several years post-hurricane compared to pre-hurricane levels. The fact that SED prevalence decreased is encouraging in that it documents some evidence of recovery. However, it is worrisome that SED prevalence did not decrease at all and, if anything, showed some evidence of an increase among youths exposed to the highest levels of stress. This finding points to the importance of expanding public health interventions to focus on the most highly exposed youths in an effort to reduce the burden of psychiatric problems. It will be important in this effort not to confuse the most highly exposed children and adolescents with the most highly disadvantaged or the most highly vulnerable youths, as we found that the continued high prevalence of SED among youths exposed to high levels of hurricane-related stress exists throughout the entire population irrespective of socio-economic or other indicators of social disadvantage and irrespective of the presence or absence of characteristics typically used as indicators of vulnerability.