Change in the health of tsunami-exposed mothers three years after the natural disaster

Abstract

Background: Women’s experiences with secondary stressors resulting from natural disasters, such as increased economic insecurity, expanded caregiving responsibilities and disrupted family life, may contribute to women’s mental and physical health problems.

Aims: The present study investigates change and stability in post-tsunami depressive symptoms and perceived physical health of tsunami-exposed mothers over three and a half years.

Methods: Using data from 160 tsunami-affected mothers, the present study uses structural equation modelling to investigate (1) change, stability, cross-lagged reciprocal influences of mental and physical health and (2) the meditation effect of negative life events on the relationship between tsunami exposure and post-tsunami depressive symptoms and perceived physical health of tsunami-exposed mothers from 2005 to 2008.

Results: Tsunami exposure contributed to depressive symptoms among mothers independently of pre-tsunami family adversities. Average depressive symptoms showed a decline whereas poor physical health showed an increase over this period. The results also revealed an interrelated health process between depression and physical health over time. Continuity of health problems were mediated by secondary stressors that also exerted an additive effect on later health problems.

Conclusions: Post-disaster intervention and recovery programmes should focus not only on mothers’ exposure to natural disasters, but also their pre- and post-natural disaster adversities. They should reach disaster-exposed mothers directly and have an integrated health approach to disrupt continuities of health problems.

Keywords

depression natural disaster physical health tsunami women’s health

Introduction

In 2004, the tsunami disaster claimed more than 200,000 human lives in several countries in south Asia and east Africa (United Nations Development Programme, 2006). The tsunami also affected millions of families through the destruction of their livelihoods, assets, houses, physical infrastructure and social organizations (Asian Development Bank, Japan Bank for International Cooperation and World Bank, 2005).

Most people who are exposed to traumatic events and social/physical devastation of natural disasters such as earthquakes and floods substantially recover from mental and physical health problems after one year (Norris et al., 2004). However, a substantial proportion of natural disaster victims continue to experience serious mental and physical health problems even several years following the disaster (Andermann, 2002; Freedy and Simpson, 2007; Norris, 2005). Furthermore, some disaster studies suggest that mental and physical health problems may mutually influence each other over time (Freedy and Simpson, 2007).

Due to the unprecedented scale of the tsunami, the magnitude of destruction and loss of lives in tsunami-exposed communities could lead to more serious mental and physical health problems than observed following previous natural disasters (Somasundaram, 2007; Wickrama and Kaspar, 2007; Wickrama and Wickrama, 2008). Moreover, the tsunami victims may be more vulnerable to unexpected difficult circumstances due to living in worse environmental conditions than before the disaster; these conditions include poor-quality housing, weakened infrastructure and a lack of resources and services necessary for recovery (Norris, 2005; United Nations, 2005).

The association between tsunami exposure and the continuity (change and stability) of health problems over time remains largely unknown as most previous natural disaster studies (a) have conceptualized health outcomes in static terms based on single time-point measures, rather than as dynamic temporal processes using repeated measures, (b) have investigated the health consequences of the disaster exposure using retrospective designs, (c) have often focused only on mental health outcomes, and (d) have investigated health consequences of the disaster exposure with some analytical limitations. Specifically, little is known about the influence of tsunami exposure on the progression of the multiple health problems of tsunami-exposed mothers over time.

Previous studies have shown that, in general, women who experience natural disaster are at greater risk for depressive symptoms and post-traumatic stress disorder (PTSD) during the short and long term (Najarian et al., 2001; Steinglass and Gerrity, 2006). These studies suggest that women’s exposure to natural disaster also results in secondary stressors, including increased economic insecurity and expanded caregiving responsibilities, and also a disrupted family life (Enarson, 2004). These secondary stressors may in turn contribute to women’s mental and physical health problems.

Thus, the present study specifically focused on tsunami-exposed mothers. Within the context of tsunami-exposed societies, several specific factors emphasize the importance of a study of tsunami-exposed mothers as a specific target population. The health implications for tsunami-exposed mothers in traditional societies such as Sri Lanka may be relatively high due to (a) high levels of family and caregiving responsibilities as compared to their spouses (Kaniasty and Norris, 1993; Norris, 2005; Norris et al., 2002), (b) potential gender inequalities in receiving social support and post-disaster services (Enarson, 2004) and (c) their poor and vulnerable working conditions; a substantial proportion of mothers in tsunami-exposed coastal villages were engaged in primary economic activities such as making coconut fibre, yarns, handlooms and dry fish as family-based cottage industries. The tsunami disaster has devastated most of these economic activities. Lack of support and services may also increase mothers’ exposure and vulnerability to secondary stressors. Only intra-group analysis can reveal unique processes involved in mothers’ natural disaster exposure, stress and health (Goodwin, 2003).

The present study

The present study investigates change and stability in post-tsunami depressive symptoms and perceived physical health of tsunami-exposed mothers. The present study uses prospective data collected from 160 mothers living in a coastal village in southern Sri Lanka, immediately after the tsunami and three and half years after the event.

This analysis addresses four specific questions (Figure 1):

Figure 1.

The theoretical model

The influences of tsunami exposure on the levels of depressive symptoms and perceived physical health of mothers immediately after the tsunami disaster (within three months).

How these mental and physical health problems continue over nearly three and a half years (stabilities).

Cross-lagged reciprocal influences between depression and physical health over time (i.e. the influence of a predictor variable X₁ (depressive symptoms at time 1) on an outcome variable Y₂ (physical health at time2), after taking into account the effect of the baseline of the same outcome variable Y₁ (physical health at time 1) as well as the influence of Y₁ on X₂ after controlling for X₁ in the same model).

Whether the associations between immediate health problems (within three months) and long-term health problems (three and half years after the tsunami) are mediated by post-tsunami stressful events (i.e. negative family life events).

When testing the hypothesized associations, the following associations were taken into account: (a) between pre-tsunami family adversity and tsunami exposure, (b) between physical health and depressive symptoms, and (c) the influence of pre-tsunami family adversity on health outcomes (Figure 1).

Tsunami exposure, immediate health outcomes and continuities

Mental health distress

Stressful experiences from natural disasters comprise two types of stressors: stressful events (e.g. deaths, injuries) and enduring strains (e.g. prolonged displacement and loss of livelihood) (Pearlin et al., 2005). In addition to stressful circumstances, the exposure to traumatic events may also contribute to feelings of distress. The conservation of resources (COR) model of stress-response provides a more specific theoretical guidance for disaster mental health studies (Hobfoll, 1989). Consistent with the COR, resources are things that people value; they tend to obtain, protect and retain these resources. Thus, resource losses such as lives, livelihood, assets, houses, family relations and social networks caused by a natural disaster are stressful and may have consequences for mental health (Hobfoll, 1988, 1989).

More importantly, resource losses from natural disaster victims are closely linked to displacement from the family home. While prolonged displacement from the family home itself operates as a powerful stressor for mothers, it may also proliferate as other stressors exert a cumulative impact on mental health. For example, displacement from the family home erodes economic, relational and physical aspects of the family. This may include a loss of livelihood of mothers (e.g. cottage industries), the weakening of family relations and the creation of family, parental and marital conflicts, along with a breakdown of mothers’ proximal social network. Particularly, parental and marital conflicts may operate as powerful stressors for mothers.

Mental health consequences of exposure to social/physical devastation and traumatic events of natural disasters include acute psychological distress and relatively chronic mental health problems. Acute psychological distress includes negative emotions, cognitive dysfunctions and distortions. Most disaster-exposed individuals recover from acute psychological distress within weeks to several months (Freedy and Simpson, 2007). The most common and relatively chronic mental health problems include depression, post-traumatic stress disorder (PTSD) and anxiety disorders (Norris, 2005). These mental health problems may continue for several years among a substantial portion of natural disaster victims (Andermann, 2002; Freedy and Simpson, 2007; Norris, 2005). The present study focused on tsunami-exposed mothers’ mental health problems and their continuation over time. It aims enhance knowledge not only of the immediate mental health consequences of natural disaster exposure but also about the continuity (change and stability) in the mental health problems of mothers.

Physical health

In addition to mental health problems, disaster-exposed individuals can be confronted with various physiological reactions contributing to several acute (e.g. minor injuries and acute illnesses/symptoms) and chronic physical health problems (e.g. major injuries and chronic illnesses; Van der Kolk et al., 1996). Clinical research has shown that stressful conditions influence physical health directly by causing deleterious effects through an interconnected set of physiological mechanisms (Adler et al., 1991; Herbert et al., 1994; Lovallo, 2005). When the source of stress is chronic (e.g. prolonged displacement or loss of livelihood), these processes may accelerate, intensify and have a sustained impact on physical health (Fremont and Bird, 2000; Harvard Medical School Health Publications Group, 1998). Following a natural disaster, victims often report physical symptoms and chronic physical health problems (Freedy and Simpson, 2007). Furthermore, research has documented that physical health problems following a natural disaster are associated with mental health problems (Van Den Berg et al., 2005). The present study focused on tsunami-exposed mothers’ physical health problems and their continuation over time. It aims to enhance knowledge not only of the immediate physical health consequences of natural disaster exposure but also about the continuity (change and stability) in the physical health problems of mothers.

Reciprocity between depression and physical health

Health problems may also proliferate across mental health and physical health. That is, in addition to the continuity of physical and mental health problems following a disaster, there would be a co-morbidity and cross-domain proliferation of health problems forming an interrelated health process (Freedy and Simpson, 2007; Taylor and Lynch, 2004). Poor mental health can contribute to physical illnesses through a number of mechanisms, including the activation of the hypothalamic-pituitary-adrenocortical (HPA) axis and sympathetic-adrenal-medullary (SAM) system, immune function effects and behavioural changes (Cohen et al., 1998).

Physical illness may also contribute to mental health problems both directly and indirectly through several mechanisms. First, internalized problems such as depression may be caused by physiological mechanisms through physical illness itself and bodily pain (Lewinsohn et al., 1996). Second, the occurrence of secondary stressful events due to impaired physical health following a natural disaster may also erode mental health over time. While on average there may be a decline in health problems following a natural disaster, it can be argued that in a substantial proportion of victims, the reciprocity between mental and physical health may initiate a long-term interrelated health process. The present study uniquely contributes to the literature by examining the reciprocal association between mental and physical health over time among mothers exposed to a natural disaster.

Mediating role of post-tsunami family negative life events

Post-tsunami mental and physical health problems may contribute to the occurrence of post-tsunami negative family life events. For example, poor mental and physical health occurring post-natural disaster may contribute to serious illnesses, deaths and loss of family income, leading to family indebtedness. Other effects of post-natural disaster trauma may include increases in marital conflict and alcohol problems; this leads to serious marital problems and work-related stressful events. In addition, poor mental and physical health post-natural disaster may contribute to poor parent–child relationships, leading to parent–child conflicts. These negative family life events in turn may escalate the mental and physical health problems of victims over time, particularly of mothers (Hobfoll, 1989). Natural disaster research has also shown that natural disaster exposure and secondary stressors may combine to influence victims’ mental health (Diane and Wee, 2005). Thus in the present study, it is expected that post-tsunami negative family life events mediate the associations between health problems immediately following the tsunami and health problems three and a half years after the tsunami. The present study fills an important gap in the literature by examining the mediating role of post-disaster negative family life events in the relationship between immediate and later health problems.

Pre-tsunami family socioeconomic adversity and health

Daily life experiences of victims’ pre-natural disaster, particularly family poverty, may also contribute to the severity of post-natural disaster mental and physical health problems (Norris et al., 2002). Family poverty exposes parents and children to adverse experiences, including the lack of food, clothing, healthcare, transportation, sanitation and housing, and to greater exposure to natural disasters because poor families mostly live near the coast in weakly built houses, resulting in poor physical and mental health (Lynch et al., 1997). These adversities are stressful and have psychological consequences for mothers in traditional societies, particularly due to their high commitment to family well-being and caregiving roles (Kaniasty and Norris, 1993; Norris et al., 2002).

In addition to family poverty, experiences of pre-tsunami negative family life events may have contributed to mothers’ post-natural disaster mental and physical health problems. Negative family life events may include serious marital and parental problems, family illnesses, deaths, job loss and debt. These stressful experiences would contribute to their pre-existing psychopathology, which is a risk for developing mental health problems related to natural disaster (Norris et al., 2002). As previously discussed, negative family life events may influence physical health through various physiological mechanisms (Lorenz et al., 2006). Thus, in the present study, the pre-tsunami family socioeconomic adversity was controlled for when examining the post-tsunami mental and physical health problems.

Methods

Sample and procedures

Site selection and participating families

Data for this study came from a survey that investigated both mothers’ and adolescent’s post-tsunami mental health. Respondent families lived in a tsunami-exposed village, Polhena, within the Matara district in southern Sri Lanka. More than 50 villages in the Matara district were exposed to the Tsunami; one village was selected as the study site using two criteria: (a) high exposure to the tsunami and (b) substantial variation in tsunami exposure among the families that lived there. Polhena village fulfilled these criteria. This village had not been exposed to the armed conflict in Sri Lanka, nor had it been exposed to a natural disaster in the past.

Polhena residents rely heavily on the fishery industry, white-fibre industry and tourism as their main occupations. The identification of families within each village relied on voter registers prepared by the Department of Elections of Sri Lanka. Of the 240 registered qualified families (families with at least one adolescent) living in Polhena, nearly 80% (N = 195) provided Wave 1 data for this study. All families displaced from their homes following the tsunami were living in temporary housing in their village of residence or in nearby interior villages when the first wave of data were collected three months after the tsunami (March/April 2005). Some of the families who did not participate had lost their mother during the tsunami. Others could not be contacted because they were moving from one shelter to another during the study period. Still others refused to participate. However, there were no significant differences between participants (80%) and non-participants (20%) in terms of government welfare receipt (food stamps and ‘Samurdi’ – based on available village data with the village officer), nor in mother’s age and family size. Also, participants’ economic (percentage of government welfare receivers) and educational characteristics (average educational level) approximated those of the general population in Sri Lanka.

The second wave of data collection followed 160 respondent families in June/July 2008. Attrition analyses showed that there were no significant differences between Wave 2 participants (N = 160) and refusers/attriters (N = 40) in terms of age, education, poverty measures, and physical and mental health measures, compared to Wave 1.

Data collection

Interview schedule and project staffing

Young women, who either possessed undergraduate degrees or were working as part-time social workers from nearby areas, were recruited to conduct the in-home interviews for data collection. Interviewers completed a two-day training session before data collection began. The first day of training focused on data collection methods and in-class exercises, with special attention given to psychiatric symptoms (i.e. depression). The second training day provided a session for reviewing and pilot testing interview procedures. Interviewer training focused mainly on collecting data from adolescents and mothers regarding exposure, stressful events, depressive symptoms and other physical health measures, but did not involve case diagnosis for psychiatric disorders. An experienced local psychiatric therapist assisted with the training session and ensured that she would be available for any necessary therapy assistance during the interview period. The primary investigator of the project remained in the area during the survey to coordinate and monitor all research activities and advise the survey team. The principal investigator regularly checked completed questionnaires for data quality and made corrective measures in interview protocol and data collection procedures when necessary. The same procedures were implemented for both waves of data collection. It took 1.5–2 hours to complete an interview. Each wave of data collection took two months to complete.

Measures

Tsunami exposure (only collected in Wave 1)

Stressful and traumatic experiences in multiple domains may combine to generate depressive symptoms (Forehand et al., 1998). The present study focuses on depressive symptoms in which a composite tsunami exposure measure was created to capture the cumulative depressogenic influence of physical destruction and traumatic events related to the tsunami. This composite score was calculated by summing the responses to questions asking about the occurrence and experiences of 12 events. The items were rated on a three-point scale (0 = ‘not occurred’, 1 = ‘occurred, I have not seen the event’, 2 = ‘occurred, I have seen the event (or experienced)’. These events included (1) a serious injury or threat to your own life, (2) death of a family member(s), (3) serious injury or threat to a family member’s life, (4) death of a close person, (5) serious injury or threat to a close person’s life, (6) death of a person(s), (7) serious injury or threat to a person’s life, (8) destruction of family house/property, (9) destruction of other peoples’ homes/property, (10) damages to other peoples’ homes/property, (11) damages to private property and (12) damages to public property/vehicles. A score more than 12 on this measure ensures that the respondent has experienced at least one event. The internal consistency (Cronbach’s α = 0.92) among these items indicated that the severity of damage in different domains was related.

Pre-tsunami family poverty (only collected in Wave 1)

Mothers responded to seven items adapted from Conger et al. (2002) that assessed the family’s pre-tsunami economic situation. Items were rated on a five-point scale (1 = ‘strongly disagree’, 5 = ‘strongly agree’). The first six items asked whether the family had enough money to afford the kind of home, clothing, furniture/household equipment, food, medical care and leisure/recreational activities they needed. The final item asked whether the family’s pre-tsunami income did not meet family expenses. Summing responses to these seven items after reverse coding the final item yielded a measure of pre-tsunami family poverty that ranged from 7 to 35. A score more than seven indicated that the family had experienced at least one economic hardship (out of seven items). Previous use of the English version of this family poverty measure in various studies with different ethnic and racial groups (e.g. Conger et al., 2002) indicated that the measure possesses good psychometric properties. This measure was pilot tested and discussed with informal groups of villagers and revised to improve clarity where necessary. The internal consistency (Cronbach’s α) of this measure was 0.80.

Pre-tsunami negative family events (only collected in Wave 1)

Mothers responded to eight items that assessed whether stressful events occurred during the year prior to the tsunami (2004) (1 = ‘yes’, 0 = ‘no’). These events included: increased conflict in your marriage, relationship with child got worse, pregnancy or related problems, serious health problems, constant quarrelling in the family, spouse lost his/her job, taking out a large loan, and death of a parent or family member. Appropriate items (considering socioeconomic and cultural context) were selected from the list of family negative life events (Dohrenwend et al., 1978), which has been used in numerous studies with different racial ethnic groups (Dohrenwend et al., 1998; Eitle and Turner, 2003). This measure was pilot tested and discussed with informal groups of villagers and revised to improve clarity when necessary. Summing responses to these eight items yielded a measure of pre-tsunami negative family life events that ranged from 0 to 8.

Post-tsunami negative family events (only collected in Wave 2)

Mothers responded to eight items that assessed whether stressful events occurred during the year (2007) (1 = ‘yes’, 0 = ‘no’). These events included: increased conflict in your marriage, relationship with child got worse, pregnancy or related problems, serious health problems, constant quarrelling in the family, spouse lost his/her job, taking out a large loan, and death of a parent or family member. Summing responses to these eight items yielded a measure of secondary family negative life events.

Depressive symptoms

Mothers’ depression was assessed in Wave 1 (2005) and Wave 2 (2008) using 20 items from the Centre for Epidemiological Studies Depression Scale (CES-D) (Radloff, 1977). The respondents indicated their frequency of experiencing depressive feelings (1 = ‘rare’, 4 = ‘most of the time’) to items such as: ‘could not shake off the blues even with help from my family and friends,’ ‘trouble keeping my mind on what I was doing,’ ‘everything I did was an effort,’ ‘my life had been a failure,’ and ‘fearful.’ Summed scores for the composite measure of a mother’s depressive symptoms could range between 0 and 60.

Previous use of the English version of the CES-D in various studies (e.g. Wickrama and Bryant, 2003) indicated that the measure possesses good psychometric properties. Moreover, the use of translated versions of the CES-D in cross-cultural mental health studies in Asian populations indicates that translated forms maintain good reliabilities and validities (Noh et al., 2007). The CES-D items were translated into Sinhalese with the help of a local psychiatrist. Cross-cultural validity was strengthened through several small pilot tests and focus groups of victims in the study area before the survey was administered by the principal investigator, who is fluent in both Sinhalese and English. Reliability was established through the repeated use of the same measure in other tsunami studies in Sri Lanka (Wickrama and Kaspar, 2007; Wickrama and Wickrama, 2008) and by calculating Cronbach’s α statistics. The internal consistencies for the depressive symptoms measures were 0.71 and 0.84 for Wave 1 and Wave 2, respectively.

Physical health

Mothers’ physical health was assessed in Wave 1 (2005) and Wave 2 (2008) using six items. The respondents indicated the degree of their agreement to the following statements (1 = ‘definitely true’, 5 = ‘definitely false’): ‘I seem to get sick a little easier than other people’, ‘I am as healthy as anybody I know’, ‘My health is excellent’, ‘For the most part, I feel healthy enough to carry out the things that I would like to do’, ‘My physical health is better than other people my age’ and ‘I have a particular physical health problem/illness’. Summed scores for the composite measure of a mother’s poor physical health could range from 5 to 30. These items were adapted from established global health measures that have been used in various studies with different ethnic and racial groups (e.g. Ngo-Metzger et al., 2008). They indicated that the measure possessed good psychometric properties. This physical health measure was pilot tested and discussed with informal groups of villagers and revised to improve clarity when necessary. The internal consistencies for physical health measures were 0.70 and 0.65 for Wave 1 and Wave 2, respectively. This indicates an acceptable level of reliability. Previous research has demonstrated that self-reports of health status are highly correlated with physicians’ assessments of morbidity (Ferraro and Farmer, 1999; Romelsjo et al., 1992).

Education

Mothers’ education was measured by the highest grade completed (self-reports).

Age

Mothers’ age was measured using self-reported age in years.

Results

Baseline characteristics

The mean age of respondent mothers was 44 years and mean education was 9 years. Before the tsunami, nearly 95% of mothers were married and 31% were partly or fully employed or engaged in economic activities. The average number of children for a family was 3.1. Most of the children of respondent mothers (90%) were older than 10 years. Before the tsunami disaster, nearly 90% of respondent families lived in permanent houses.

Prevalence rates for depression

Table 1 presents descriptive statistics of all study variables. Mean of depressive symptoms was 29.14 (range 8–50) in 2005, and 17.15 (range 3–47) in 2008, showing an average decline in depressive symptom levels of mothers. However, poor physical health showed an average increase, with a mean of 9.71 and 12.02 in 2005 and 2008, respectively. Means of pre-tsunami (2004) and post-tsunami (2007) negative family life events were 0.82 and 1.40, respectively, showing a significant increase (p < 0.05) in negative family negative events.

Table 1.

Descriptive statistics of the study variables

Variable name	Minimum	Maximum	M	SD
Mother’s age	29	60	43.20	7.54
Mother education (years)	2	13	1017	0.56
Family poverty	8	31	19.52	4.30
Family NLE (W1)	0	5	0.82	1.01
Tsunami exposure	7	24	13.96	3.81
Depressive symptoms (W1)	8	50	29.13	9.93
Depressive symptoms (W2)	3	47	17.15	10.32
Poor physical health (W1)	5	25	9.71	5.17
Poor physical health (W2)	5	25	12	5.69
Family NLE (W2)	0	5	1.40	1.34

Structural equation models

Figure 2 presents the hypothesized model corresponding to the theoretical model shown in Figure 1 without secondary negative life events as a mediator; this presents the tested structural equation model (SEM) with unstandardized path coefficients. An unstandardized regression coefficient (β) for a path can be defined as the number of units changed in the dependent variable for one unit change in the independent variable. Maximum likelihood estimates for the model coefficients were obtained using the Amos 4.0 software package (Arbuckle and Wothke, 1999).

Figure 2.

Tsunami exposure and progression of mother’s health problems (unstandardized regression coefficients,* p < 0.05)

Figure 2 presents the SEM model predicting poor physical health and depressive symptoms of mothers immediately following the tsunami disaster, after controlling for pre-tsunami family poverty, family negative life events, mothers’ education and age. As expected, tsunami exposure predicted mothers’ depressive symptoms in 2005 (β = 0.42, p < 0.05, explained variance = 0.18). That is, 1 unit increase in tsunami exposure resulted in a 0.42 unit increase in depressive symptoms of mothers. However, contrary to expectations, neither tsunami exposure nor family characteristics predicted mothers’ poor physical health in 2008 (β = -0.18, not significant for tsunami exposure). Both poor physical health and depressive symptoms showed low stabilities over a three-year period from 2005 to 2008 (β = 0.26 and 0.16, respectively, p < 0.05). Consistent with the cross-lagged hypothesis, poor physical health and depressive symptoms in 2005 contributed to depressive symptoms (β = 0.30, p < 0.05) and poor physical health (β = 0.11, p < 0.05) in 2008, suggesting an interrelated health process over time. Tsunami exposure was not directly associated with poor physical health and depressive symptoms in 2008. The model fitted the data well, as indicated by χ² statistics of 12.86 with 16 degrees of freedom (χ²/df ratio = 0.80) and the Comparative Fit Index (CFI = 1.0).

Figure 3 presents the complete hypothesized model corresponding to the theoretical model shown in Figure 1. Secondary negative life events (occurring in 2007) were associated with tsunami exposure (β = 0.10, p < 0.05), and both poor physical health (β = 0.04, p < 0.05) and depressive symptoms (β = 0.02, p < 0.05) in 2005. In turn, secondary negative life events significantly influenced both poor physical health (β = 0.88, p < 0.05) and depressive symptoms (β = 2.57, p < 0.05) in 2008. As shown in Figures 2 and 3, the association between depressive symptoms in 2005 and 2008 diminished substantially from 16 to 0.10 and became non-significant. The path from poor physical health in 2005 to depressive symptoms in 2008 dropped from 0.30 to 0.19, becoming non-significant. Other paths between health problems in 2005 and 2008 also dropped by small amounts. These results provide evidence for the mediational role of secondary family negative life events on the longitudinal associations of health problems (Baron and Kenny, 1986). The model explained 14% and 15% variance in poor physical health and depressive symptoms in 2008, respectively. The model also explained 11% of the variance in secondary negative life events. The results suggest that, in addition to a mediational effect, secondary negative life events also had an additive influence on health problems in 2008.

Figure 3.

The mediational effect of secondary negative life events on the continuity of mothers’ health problems (unstandardized regression coefficients, * p < 0.05)

Discussion

The findings of this study generally support the hypothesized model in that the tsunami exposure contributed to early depressive symptoms among mothers independently of pre-tsunami family adversity. However, tsunami exposure was not significantly associated with mothers’ poor physical health. Post-tsunami poor physical health and depressive symptoms continued for more than three years. Although depressive symptoms showed an average decline, poor physical health showed an average increase over this period. The results also revealed cross-lagged reciprocal influences between depression and physical health over time. Additionally, the results showed that some of the associations between earlier health problems and health problems after the tsunami, as well as long-term health influence of the tsunami exposure, were mediated by post-tsunami family stressful events.

The average levels of depressive symptoms were higher than the observed average level of depressive symptoms following previous natural disasters. This may be attributed to the unprecedented scale of the tsunami disaster (Somasundaram, 2007; Wickrama and Wickrama, 2008). It may also be attributed to the fact that previous natural disaster studies have investigated adult victims in general, whereas the present study focused only on disaster-exposed mothers. As previously argued, mothers in traditional societies may be more vulnerable to natural disasters than fathers due to their (a) higher commitment to family and caregiving roles, (b) greater socioeconomic adversities, (c) receiving less social support and services, and (d) greater loss of social resources (e.g. informal social networks) compared to fathers (Enarson, 2004; Kaniasty and Norris, 1993; Norris, 2005; Norris et al., 2002). However, the results of this longitudinal study showed that the stability of depressive symptoms was low and the average level also decreased over the study period. The decline in the average level of depressive symptoms with a low stability indicates that although most of mothers recovered over the study period, there were inter-individual differences in the rates of recovery.

The absence of a direct influence of tsunami exposure on mothers’ physical health may be attributed to several factors. First, most mothers who were physically affected by the tsunami were those who died instantly; the majority of tsunami deaths were women (Nishikiori et al., 2006). Second, injuries caused by the tsunami to the surviving mothers would have improved by the time of data collection (after three months). However, the increase in the level of poor physical health over time suggests that certain physical health problems may manifest at a later time. These findings enhance knowledge about long-term physical health consequences of natural disaster-exposed mothers because, to the authors’ knowledge, previous studies have not investigated physical health problems of mothers over time.

Cross-lagged influences showed that early reported depression contributed to poor physical health later, and early poor physical health contributed to later depressive symptoms (Figure 2). These reciprocal influences create post-natural disaster interrelated health processes over time. It seems that although natural disaster exposure does not directly influence later physical health or depression, it initiates an interrelated health process by creating initial health problems. Only a prospective longitudinal study, such as this, provides an appropriate opportunity to understand changes in health problems and interrelated processes over time (McNally et al., 2003). Previous studies were not able to show such interrelated health processes involving mental and physical health, because the research consistently lacks longitudinal health data and it is limited in the use of analytical techniques. Thus, the present study fills an important gap in natural disaster research.

The results showed that continuity of health problems are mediated by secondary stressors such as family negative life events. These secondary stressors were influenced not only by initial poor physical health and depression, but also by tsunami exposure directly. Secondary stressors were responsible for more than half of the explained variance of poor physical health and depressive symptoms three years after the tsunami. The results suggest that secondary stressors exert not only a mediating effect but also an additive effect on later health problems. The present prospective longitudinal study provided an appropriate opportunity to understand associations of changes in health problems with secondary risk factors (McNally et al., 2003). To the authors’ knowledge, no natural disaster study has statistically demonstrated the mediational effect of secondary stressors on the exposure–health relationship, nor on the continuity of health problems.

Furthermore, the present study only focuses on tsunami-exposed mothers. This is a special target group of the tsunami-exposed population. This intra-group analysis revealed important associations and processes that would otherwise be obscured in an analysis with a representative sample. These observed associations and processes may be unique to mothers.

Findings from this study suggest a number of important practical implications for offering support to tsunami-exposed communities. First, tsunami-exposed mothers showed higher prevalence in depression three and half months after the tsunami. This has been attributed not only to tsunami exposure, but also to family adversity. In addition, secondary negative family life events contributed to the continuity of their health problems. Thus, health recovery programmes should focus not only on mothers’ exposure to natural disaster, but also their pre-natural disaster and post-natural disaster adversities. Second, natural disaster recovery programmes should reach disaster-exposed mothers directly, therefore more effectively eliminating potential gender bias or discrimination of existing delivery systems. Third, physical and mental health problems continued as an interrelated process. Thus, natural disaster health recovery programmes should have an integrated health intervention approach to disrupt continuities of health problems.

Limitations

Several important limitations to this pilot study deserve attention. First, some of the study measures, including depression and physical health, only demonstrate adequate psychometric properties. While depression measures were pilot tested and revised to improve clarity when necessary, internal consistencies for the depressive symptoms measured in Wave 1 slightly exceeded 0.70, suggesting potential difficulties due to translation. Similarly, the internal consistencies of physical health measures suggested weak or moderate associations among constituent items. Future research efforts should attempt to improve these instruments and demonstrate that they are culturally valid and reliable assessment tools.

A second potential limitation involves the representativeness of the study sample. For example, the study village and/or its inhabitants may not represent the larger population of tsunami-exposed mothers in Sri Lanka in terms of socioeconomic characteristics. Although site selection focused on locations that were representative of villages across the Matara district in terms of poverty rates and accessibility, it is possible that the villages selected were not representative of tsunami-exposed villages outside the Matara district. In addition, although the rate of participation in the village was quite high, approximately only 20% of voter-registered qualified families did not participate in the present study. A third limitation involves causal direction for the observed associations. That is, these data do not eliminate the possibility of reversed or reciprocal causality. For example, mothers with high levels of depression could provide negatively biased reports of secondary negative family life events.

Conclusions

Despite the potential limitations of this study, it has identified long-term mechanisms through which tsunami exposure influences the mental health of mothers. These findings also provide potentially important suggestions and clues for future research that extensively examines post-natural disaster recovery using improved research designs that include optimal measures of study constructs.

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