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Mathematica Policy Research, Inc, Princeton, New Jersey
| ABSTRACT |
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METHODS. A cross-sectional survey of 2870 mothers of 3-year-old children was conducted in 20012003 in 18 large US cities. On the basis of the adult food-security scale calculated from the US Household Food Security Survey Module, mothers were categorized into 3 levels: fully food secure, marginally food secure, and food insecure. The 12-month prevalence in mothers of a major depressive episode and generalized anxiety disorder was assessed by the Composite International Diagnostic Interview-Short Form. A child behavior problem in
1 of 3 domains (aggressive, anxious/depressed, or inattention/hyperactivity) was based on the Child Behavior Checklist.
RESULTS. Seventy-one percent of the respondents were fully food secure, 17% were marginally food secure, and 12% were food insecure. After adjustment for sociodemographic factors plus maternal physical health, alcohol use, drug use, prenatal smoking, and prenatal physical domestic violence, the percentage of mothers with either major depressive episode or generalized anxiety disorder increased with increasing food insecurity: 16.9%, 21.0%, and 30.3% across the 3 levels. Among children, after further adjustment for maternal major depressive episode and generalized anxiety disorder, the percentage with a behavior problem also increased with increasing food insecurity: 22.7%, 31.1%, and 36.7%.
CONCLUSIONS. Mental health problems in mothers and children are more common when mothers are food insecure, a stressor that can potentially be addressed by social policy.
Key Words: child behavior depression anxiety hunger food supply child nutrition child preschool
Abbreviations: CIDI-SFComposite International Diagnostic Interview-Short Form MDEmajor depressive episode GADgeneralized anxiety disorder DSM-IVDiagnostic and Statistical Manual of Mental DisordersFourth Edition CBCLChild Behavior Checklist ADHDattention-deficit/hyperactivity disorder ORodds ratio CIconfidence interval
Stressful social circumstances, particularly constrained economic resources, have been linked to behavioral problems in young children1,2 and to symptoms of depression and anxiety in mothers.3,4 Reducing the risk of these mental health problems in families might be possible if specific stressors that could feasibly be addressed by social policy were identified. Qualitative research has shown that food insecurity, defined as a limited or uncertain availability of nutritionally adequate and safe food resulting from constraints in economic resources,5 is a particular form of material deprivation that can stress mothers and their young children.69 Food insecurity is also a stress that may potentially be relieved by existing federal food assistance programs such as the Food Stamp Program or the Special Supplemental Nutrition Program for Women, Infants, and Children, but the impact of such programs is difficult to study.10,11
The biological plausibility of a causal association between food insecurity and mental health problems is supported by experimental studies in nonhuman primates in which nursing mothers are exposed to a procedure called variable foraging demand. In this procedure, food is available to mothers in adequate amounts, but mothers face an unpredictable variability in the effort required of them to obtain the food.12 Mothers exposed to this stressor have impaired interactions with their offspring. In turn, the offspring exhibit insecure attachment, affective changes characterized by anxiety and depression, and difficulty with peer interaction that persists even after the maternal stress ceases.12,13 These behavioral changes are also associated with parallel changes in mother and offspring in neurobiological systems related to stress response and affect.14,15 On the basis of such findings, it is possible that food insecurity in humans leads to maternal emotional distress such as symptoms of anxiety and depression, which, in turn, contributes to child behavior problems.
In epidemiologic studies, food insecurity has been associated with childhood behavior problems such as aggression, anxiety, depression, hyperactivity, and not getting along with peers.1619 However, some of these studies did not control for other socioeconomic stressors,17,18 and each of these studies, expect for one, involved only low-income families living in 1 or 2 cities. The single study with a more diverse sample of US families did not use standardized measures of children's behavior problems and did not assess preschool-aged children,19 who may be particularly vulnerable to the stress arising from food insecurity. Furthermore, none of these studies measured food insecurity using the US Household Food Security Survey Module,20,21 now considered the standard for assessing household food security. Although there have been large studies examining the relationship between food security and mental health in mothers,2225 none have included data on children's mental health.
Using data on urban, 3-year-old children and their mothers from a recent US birth-cohort study,26 we examined the association of maternal food insecurity with depression and anxiety in mothers and with behavior problems in their preschool-aged children. In addition, we determined whether maternal depression and anxiety explained any of the association between maternal food insecurity and child behavior problems.
| METHODS |
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Mothers were surveyed in person shortly after delivery and by telephone
1 and 3 years after delivery. In 18 of the 20 cities, an additional survey (79% completed in person and 21% completed by telephone), also conducted 3 years after delivery, asked mothers about food insecurity and their children's behavior. Of the 4242 mothers who were enrolled at delivery in the 18 cities, 2886 (68%) participated in the additional survey 3 years after delivery. A comparison of these 2886 mothers, who are the focus of this report, to the 1356 mothers who were not followed up, showed no significant differences at the time of delivery in household income, age, marital status, or education level. However, the racial/ethnic composition of the mothers was different between those in our study sample and those who were not followed up (non-Hispanic white: 23% vs 21%; non-Hispanic black: 51% vs 46%; Hispanic: 23% vs 28%; other race/ethnicity: 3% vs 5%; P < .001).
Maternal Mental Health Conditions
Maternal mental health outcome measures were derived from version 1.0 of the World Health Organization Composite International Diagnostic Interview-Short Form (CIDI-SF), which was administered to the mothers 3 years after delivery.27 Using the suggested CIDI-SF scoring method, we defined 2 outcomes: the 12-month prevalence of a major depressive episode (MDE) and of generalized anxiety disorder (GAD).28 To be classified as having an MDE, a mother had to report having had a 2-week period in the preceding year during which she experienced either dysphoric mood (felt sad, blue, or depressed) or anhedonia (lost interest in most things) to a significant degree (the symptom lasted for at least most of the day, almost every day). She also had to report having had at least 3 of the other symptoms of major depression listed in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV).29
Because version 1.0 of the CIDI-SF contained a minor error in the question-skip pattern,30 some mothers who reported feeling sad or depressed were not subsequently asked the questions about the intensity of their symptom of anhedonia (129 [4.5%] of the mothers in our sample). To avoid underestimating the prevalence of MDEs in the sample, we classified 97 (3.4% of our sample) of these mothers as having an MDE because they reported some degree of anhedonia and at least 2 of the other DSM-IV depressive symptoms. Our findings were unchanged when we ran our analyses by classifying these 97 mothers as not depressed.
Child Behavior Problems
Child behavior variables were derived from the Child Behavior Checklist (CBCL) for children 1.5 to 5 years of age, which was also administered to mothers 3 years after delivery. The CBCL is a validated instrument in which a mother is given a series of statements about her child's behavior and asked whether each statement was not true, sometimes or somewhat true, or very true or often true.31 Subscales, derived from the CBCL items, were used to determine behavior problems in 3 domains: aggressive (19 items), anxious/depressed (8 items), and attention-deficit/hyperactivity (6 items). All 3 of these subscales assess behavior problems that have been shown in previous studies to be associated with food insecurity.1618
The first 2 subscales were empirically derived. However, the third subscale was derived in a study32 in which 16 child psychiatrists and psychologists, each of whom had published research on children's behavioral and emotional problems, were asked to rate those items from the CBCL that were most consistent with the diagnosis of attention-deficit hyperactivity disorder (ADHD) according to the DSM-IV. The criterion for selecting these 6 scale items was that they each be rated as "very consistent" with ADHD by at least 10 of the 16 raters. We refer to this third behavior domain as "inattention/hyperactivity" because the diagnosis of ADHD is not customarily made in preschool-aged children and because this scale is not a diagnostic instrument for ADHD.
For each of the 3 behavior domains we computed a score from the items that make up the scale. If data were missing for >3 items on the aggressive scale or >1 item on either of the other scales, we considered the behavior outcome missing for that child. Otherwise, we replaced the value for the missing item with the median value of the other answered items on the scale. We then converted the scale score to a percentile, which was based on normative data,31,33 and children with scale scores
93rd percentile (T score
65) were considered to have a significant problem in that behavior domain.
Maternal Food Security
Our measure of maternal food security was based on the 10 household- and adult-referenced questions in the US Household Food Security Survey Module,20,21 which was administered to the mothers 3 years after delivery. The items ask about the previous 12 months (Table 1), and they assess food security along a continuum by asking about a range of conditions and behaviors experienced when the quality or amount of available food is constrained as a result of lack of money or other resources. Of these 10 items, 7 specifically reference the adult respondent, and the others reference the household. Because adults in households without children can answer these questions, this scale is usually referred to as the adult scale; however, here we call it the maternal scale, because the respondents were all mothers of preschool-aged children. We computed the number of positive responses (the total number of food-insecure conditions the mother reported) using previously described procedures to score item responses as positive and to code any missing responses.20 Mothers with
3 positive items were considered "food insecure,"20 and we further differentiated households that were "marginally food secure" (those with 1 or 2 positive responses) from those that were "fully food secure" (no positive items).34,35
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Sociodemographic Factors
Data on household income and the number of children in the household were not available from the year-3 survey, so we used data from the year-1 survey. If these data were missing from the year-1 survey, we used data from the survey at delivery (110 and 126 cases for income and number of children, respectively). The income/poverty ratio was calculated as the household income divided by the income at the federal poverty line for the year of the income report and the household size. Data on maternal race/ethnicity, education level, relationship/marital status, and months of employment in the previous year were obtained from the survey 3 years after delivery. Mothers were considered to have experienced material hardship during the preceding 12 months if, as a result of lack of money, they had been evicted from their home or apartment, had service turned off by the gas or electric company, or had been refused the delivery of heating oil. Finally, the mother reported whether the father had ever been in jail during his lifetime.
Maternal Physical Health and Substance Use
Mothers were asked to rate their health as excellent, very good, good, fair, or poor. Binge drinking was classified as the mother reporting that during the past year she had
4 drinks in 1 day a few times a month or more often than that. On the basis of her response to CIDI-SF questions, the mother was considered to use illicit drugs if she reported smoking marijuana or hashish at least "a few times" during the past year or reported ever using drugs (on her own) during the past year from any of the following classes: (1) sedatives or sleeping pills, (2) tranquilizers or "nerve pills," (3) amphetamines or other stimulants, (4) analgesics or other prescription painkillers, (5) inhalants, (6) cocaine, crack, or freebase, (7) LSD or other hallucinogens, or (8) heroin.
Prenatal Factors
Maternal smoking during the pregnancy and prenatal physical domestic violence were derived from questions on the survey at delivery. Prenatal physical domestic violence was considered to have occurred if the mother reported that during pregnancy the child's father sometimes or often "hit or slapped [her] when he was angry." It was also considered to have occurred if "violence [or] abuse" was among the reasons the mother was no longer romantically involved with, living with, or married to the father at the time of the child's birth.
Statistical Analysis
The final analytic sample contained 2870 cases. Of the 2886 survey respondents, 16 were excluded because of missing data: 9 were missing data on all 3 child behavior problems, 6 on both maternal mental health measures, and 1 on food security.
Each child behavior problem (aggressive, anxious/depressed, and inattention/hyperactivity) and each maternal mental health condition (MDE and GAD) was examined as a separate outcome because food insecurity is a stress that could result in different behavioral and emotional responses across individuals. We also examined the 2 summary variables (the presence of either maternal mental health condition and the presence of any child behavior problem) because these problems/conditions often co-occur.
All analyses were conducted by using categorical variables to facilitate the clinical interpretation of our results.
2 tests were first used to examine the primary bivariate associations of interest (between the level of maternal food insecurity and each of the key outcome variables [maternal mental health conditions and child behavior problems]). Similarly,
2 tests were used to examine the bivariate relationship of the 13 covariates to the outcome variables and to food insecurity.
We then used logistic-regression models to control for covariates. In these models, with maternal mental health conditions and child behavior problems as the outcome variables, we determined the odds of the outcome as the level of maternal food insecurity increased, using those who were "fully food secure" as the reference group. From these regression models, we also computed the adjusted prevalence of the maternal mental health conditions and child behavior problems at each of the 3 levels of food security.
In a final set of models, with the child behavior outcomes as the dependent variables, we entered maternal mental health as an additional independent variable to determine to what extent, if any, maternal mental health explained the relationship between food security and children's behavior problems. In addition, we used these models to assess whether there was a significant interaction between the level of food security and maternal mental health, maternal race/ethnicity, or household income.
Although we collected data on all 18 questions in the US Household Food Security Survey Module, we do not present our analyses on the 8 child-referenced questions that make up the children's food-security scale. Our results using this scale and placing children into 3 categories of food security (0 positive responses, 1 or 2 positive responses, and
3 positive responses) were not meaningfully different from our results with the maternal scale (data are available on request). Of the mothers who were food insecure, 27.4% of their children were food insecure (
3 positive responses on the children's scale). However, of the mothers who were marginally food secure, only 0.6% of their children were food insecure. The maternal scale is presented because we were interested in examining whether the maternal experience of food security and its impacts on maternal mental health might be a possible mechanism by which a household's food insecurity is associated with child behavior.
| RESULTS |
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6 positive items, a group customarily designated as "food insecure with hunger."20
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2 test, P = .02 for maternal binge drinking and P
.001 for all other associations; data not shown).
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1 behavior problem: 36.1% vs 18.5% [P
.001 for all comparisons]). The unadjusted odds of all 3 child behavior problems and the unadjusted odds of having
1 of these problems increased with the mothers' level of food insecurity (Table 5). In logistic-regression models that adjusted the odds of child behavior problems for maternal mental health (having a mother with either an MDE or GAD), there was still a graded risk relationship between the level of maternal food security and all the child behavior outcomes (Table 5). With this adjustment for maternal mental health status, there were only modest decreases (13.3% to 15.6%) in the odds ratios (ORs) for behavior problems among children of food-insecure mothers, suggesting that maternal mental health explained a small portion of the risk of child behavior problems associated with maternal food insecurity.
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| DISCUSSION |
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The results of 3 large studies examining the association between food security and symptoms of depression in women were consistent with our own.22,23,25 Two of these studies,22,25 like our own, used the CIDI-SF to assess mental health symptoms. However, they used food insufficiency as their "exposure," which is a measure of insufficient food intake that represents a greater level of food insecurity than the threshold we used in our analyses.36 Both studies found that the adjusted risk of an MDE was 2 to 3 times higher for women who reported food insufficiency. In contrast to our findings, the adjusted risk of GAD, measured in one of the studies,25 was not increased. The third study,23 which used a 3-question screener37 to assess depressive symptoms among mothers of infants and toddlers in a convenience sample at urban pediatric medical centers, found food insecurity to be twice as common in mothers with a positive depression screen.
One previous study of the relationship between food security and children's behavior problems involved preschool-aged children.16 The subjects were 152 children in Worchester, Massachusetts, half of whom were homeless. Consistent with our own findings, levels of internalizing behavior problems increased with the level of food insecurity even after adjusting for multiple potentially confounding factors. Other studies in school-aged children, which did not control for such factors, have also shown that food insecurity is associated with higher levels of parent-reported behavior problems17,18 and of teacher-reported hyperactivity.17
Our study sample was limited to children born in large cities, and, by design, it contained many poor and unwed mothers. Nonetheless, the prevalence of adult food insecurity was similar in our study population (12.2%) to the prevalence among all US adults in 2004 (10.6%) (M. Nord, PhD, written communication, March 10, 2006). Although there were only minor differences between our study sample and those in the birth cohort who were lost to follow-up, we cannot exclude the possibility of some selection bias. Hispanic mothers, for example, were less likely to be followed up, but we found that race/ethnicity did not modify the association between maternal food security and child behavior problems.
There were some limitations to our outcome measures. Maternal MDEs and GAD were not based on a full diagnostic interview, and symptoms of these conditions could have altered the mothers' perceptions of their children's behavior.38 We did not have data on observed child behavior or mother-child interactions. Although our data were obtained from a prospective birth-cohort study, our analysis was cross-sectional. Therefore, it is difficult to make causal inferences between food security and mental health. We attempted to control for multiple covariates, including other forms of material deprivation not related to food, but some of the association we found could still be explained by unmeasured factors. It is also possible that there was some misclassification of household income, because we used income reports from mothers 1 year after delivery rather than 3 years after delivery. Consistent with a causal association, however, are the biological plausibility of such an association, the graded relationship between food security and mental health problems, and the consistency of findings for outcomes within and across mothers and children.
It is possible that mental health problems in the mothers caused socioeconomic difficulties, such as reduced success in education and employment or relationship difficulties with the child's father, that ultimately led to food insecurity. However, the fact that controlling for these mediating socioeconomic factors did not eliminate the association argues against reverse causality. In addition, results from the one study, which longitudinally assessed both food insufficiency and mental health in women, suggest that changes in food-insufficiency status are associated with changes in depression status.24 We know of no experimental interventions to reduce food insecurity that have examined impacts on mental health.
The mechanisms linking food insecurity to children's mental health problems are uncertain. Among preschool-aged children, poor dietary quality does not seem to be the most likely mechanism, because differences in nutrient intakes have not been observed between preschool-aged children in food-secure and food-insecure households.3941 However, data from these studies are based on dietary recalls, which can contain substantial measurement error. It is possible that a deficiency of a micronutrient, such as iron,42 could occur among some children whose mothers report food insecurity and that this deficiency could impact children's behavior.43
Although mothers seem to buffer their young children from the nutritional impacts of household food insecurity, they may not necessarily buffer children from the psychological impacts.7 Qualitative research on mothers' experiences of food insecurity69 and experimental studies on the behavioral response of nonhuman primates to variable foraging demand with adequate food supply12,13 suggest that food insecurity may lead to behavior problems in children through psychological stress.
Although multiple socioeconomic factors, as our own data show (Table 3), are known to be associated with an increased risk of mental health problems in adults and children, food insecurity may be particularly stressful in families with young children. Lacking adequate resources to provide a certain supply of food could threaten a mother's confidence in her ability to nurture her young child and could thus produce significant maternal distress. This distress, expressed as anxiety, sadness, preoccupation, or irritability, might occur at levels below the thresholds for an MDE or GAD but still lead to impaired mother-child interaction and attachment as well as significant behavior problems in children. This could explain our finding that maternal MDEs/GAD did not seem to be a major mediator between maternal food insecurity and child behavior problems.
Certain stresses early in life, such as emotional, physical, or sexual abuse, increase the risk of later mental health problems,44 possibly by altering brain neurochemistry45 and morphology.46 Food insecurity may be a form of early life stress that can also have long-term health implications. Studies of variable foraging demand suggest that the stress associated with food insecurity might express itself through neural circuits involving corticotropin-releasing factor.47 These are the same neural mechanisms by which other early life stresses are hypothesized to result in a distinct biological subtype of adult depression.48 Future studies should examine whether household food insecurity increases a child's susceptibility to later mental health problems.49 Social policy can address food insecurity more directly than it can address many other early-life stresses, and doing so can enhance the well-being of both mothers and children.
| ACKNOWLEDGMENTS |
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We thank Ram Chandran, PhD, Jeremy D. Coplan, MD, John G. Kral, MD, Mark Nord, PhD, Leonard A. Rosenblum, PhD, Louisa B. Tarullo, EdD, and Christopher A. Trenholm, PhD, for critical review of earlier drafts of this manuscript.
| FOOTNOTES |
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Address correspondence to Robert C. Whitaker, MD, MPH, Mathematica Policy Research, Inc, PO Box 2393, Princeton, NJ 08543-2393. E-mail: rwhitaker{at}mathematica-mpr.com
The authors have indicated they have no financial relationships relevant to this article to disclose.
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