In a national study of over 2400 urban, 3-year-old children, the odds of obesity were 50% higher for those who experienced neglect in the prior year compared to those who never experienced an episode of neglect, suggesting that some aspects of early parent-child interaction that are not directly related to diet and physical activity may influence the risk of childhood obesity. This finding for neglect persisted after adjusting for maternal obesity and multiple sociodemographic covariates. However, we found no association between obesity and two other types of child maltreatment—corporal punishment and psychological aggression.
There have been few population-based studies of the relationship between obesity and child maltreatment. To our knowledge this is the first study to have examined the association between child maltreatment and obesity during childhood. Excluding the area of sexual abuse, there have been only two studies of adult obesity and childhood maltreatment. In a prospective study of 756 Danish school children who were 9 to 10 years-of-age, Lissau and Sorenson (1994)
found that the odds of obesity in young adulthood, 10 years later, were increased 7 to 10 times among those who were “neglected” as children. Children were considered neglected on the basis of being rated by their teacher as having “no parental support” or by the school medical service (mainly school nurses) as having hygiene that was “dirty and neglected.” The authors controlled for socioeconomic status and obesity in childhood, but not for parental obesity. Only 38 subjects (5.0%) were classified as obese adults (BMI ≥ 26.9 kg/m2
for men and ≥ 26.3 kg/m2
for women). In a California health maintenance organization, Williamson and colleagues (2002)
studied 13,177 adults, one fourth of whom were obese (BMI ≥ 30 kg/m2
) at a mean age of 56 years. After controlling for multiple adult characteristics, including education, smoking, and physical activity, the authors demonstrated an approximately 30 to 40% increase in the odds of obesity among those who reported either frequent verbal or physical abuse before 18 years of age. Neglect was not assessed in this study.
The underlying mechanism by which child maltreatment may lead to later obesity is uncertain. One potential mechanism is that maltreatment conditions the child to respond to stress by increasing food intake and/or decreasing activity (Greeno & Wing, 1994
; Steptoe, Wardle, Pollard, Canaan, & Davies, 1996
). Childhood maltreatment is a well-established risk factor for later depression and anxiety (Mullen, Martin, Anderson, Romans, & Herbison, 1996
; Oakley-Browne, Joyce, Wells, Bushnell, & Hornblow, 1995
; Portegijs, Jeuken, van der Horst, Kraan, & Knottnerus, 1996
), and several studies have now shown that symptoms of depression and anxiety in childhood are associated with the later development of obesity, particularly in females (Anderson, Cohen, Naumova, & Must, 2006
; Goodman & Whitaker, 2002
; Hasler et al., 2005
; Pine, Goldstein, Wolk, & Weissman, 2001
; Richardson et al., 2003
). Depression and/or anxiety resulting from maltreatment may be associated with neuro-endocrine responses that alter metabolism, activity levels, or appetite (Bjorntorp, 2001
; Chrousos, 2000
; Nemeroff, 2004
Although there may be no true association between childhood obesity and either corporal punishment or psychological aggression, a true association could have been missed in this study for several reasons. The impact of these two forms of maltreatment on obesity may only occur when these types of maltreatment are of a more severe or chronic nature than we assessed. It is also possible that the impact on obesity does not become apparent until an older age. Although we saw a range of exposures to these two types of maltreatment, some form of each type of maltreatment was experienced by nearly all children in the study, making a truly “unexposed” group hard to identify.
The items in the corporal punishment and psychological aggression scales of the CTSPC are all common discipline techniques which parents use in response to their children’s misbehavior and which a young child might come to anticipate. In contrast, the neglect items are parent behaviors, which are not usually prompted by the child’s misbehavior and which, in the child’s mind, may not seem like a predictable consequence of misbehavior. It may be the unexpected or non-contingent nature of neglect that heightens the child’s emotional distress. In this regard, the emotional impact of neglect may be more like those of sexual abuse, another form of maltreatment that the child might not perceive to be a consequence of misbehavior even if the child internalizes the maltreatment as a punishment. The relationship between childhood sexual abuse and later obesity, especially among females, has been shown in several studies (Gustafson & Sarwer, 2004
A final explanation for our contrasting findings across types of maltreatment, is that the common practice of corporal punishment and psychological aggression toward preschoolers may reflect the level of the child’s gross motor activity at an age when many parental disciplinary efforts are directed at trying to shape their children’s natural impulses to explore their environment and to establish autonomy (Straus & Stewart, 1999
). Two-year olds who are more frequently “on the move” may have lower BMI and also tend to experience more parental discipline.
In interpreting our results, several limitations must be considered. Although the sample contained families from 15 states with a broad range of household income and maternal education levels, our findings are not meant to apply to all US 3-year-old children. The children in the study were living in large metropolitan areas and a high proportion of the children were born to unwed parents. In addition, mothers who did not speak English or Spanish were excluded, as were some mothers less than 18 years of age. In addition, the study involved only half the original birth cohort. Our results were not weighted for this non-response or for the sampling design, and it is possible that either of these factors introduced bias. Those who had height and weight measurements had a different racial/ethnic composition and lower income levels than those who did not have these measurements. We cannot determine how these differences might have influenced our findings about the relationship between maltreatment and obesity. However, in multivariate analyses, we found no significant interactions between our maltreatment variables and either race/ethnicity or income.
Our measurements of child maltreatment were based on parental self-reports and did not include measures of severe physical maltreatment or sexual abuse. In addition, we are unable to make inferences about causality from this cross-sectional study—either that neglect causes obesity or that obesity causes neglect. There may also be unmeasured factors that confound the relationship between neglect and obesity. Theoretically, these unmeasured factors would include diet or activity behaviors, but previous studies of preschool children have not shown any consistent relationships between measures of these behaviors and obesity (Reilly et al., 2005
). We did account for the factors which have shown the strongest relationship to obesity at this age—the children’s birth weight and the mothers’ BMI, race/ethnicity, education, income, and smoking status (Whitaker, 2004b
Evidence is now emerging that child maltreatment may be associated with later obesity. Child maltreatment is already well-established as a precursor of several mental health disorders, particularly mood and anxiety disorders (Kessler, Davis, & Kendler, 1997
). Together these findings support other evidence that poor mental health and obesity, which are common, costly, and difficult to treat, are also related to each other (Faith, Matz, & Jorge, 2002
; Whitaker, 2004a
). If it can be established that child maltreatment is a modifiable risk factor that is shared by these chronic adult conditions, this might lead to the development of new obesity prevention strategies—ones that begin very early in life, include efforts not solely focused on diet and activity, and prevent more than obesity.
In addition to conducting more epidemiologic investigations of the association between maltreatment and obesity, future research should also focus on understanding potential mechanisms for this association. Specifically, that research might attempt to determine whether a child’s stress response, which is entrained early in life by maltreatment and which can later be activated by other stressful situations (McEwen, 2003
), alters the brain mechanisms that regulate appetite or activity level.
In conclusion, our findings indicate that 3-year-old children have an increased risk of obesity if they experienced neglect in the prior year. This study adds to the existing evidence that mental health conditions and obesity have some shared developmental origins. Maintaining a healthy weight may be another positive outcome for children that could result from efforts to prevent child neglect.