Associations between overweight, peer problems, and mental health in 12–13-year-old Norwegian children
Overweight and mental health problems represent two major challenges related to child and adolescent health. More knowledge of a possible relationship between the two problems and the influence of peer problems on the mental health of overweight children is needed. It has previously been hypothesized that peer problems may be an underlying factor in the association between overweight and mental health problems. The purpose of the present study was to investigate the associations between overweight, peer problems, and indications of mental health problems in a sample of 12–13-year-old Norwegian schoolchildren. Children aged 12–13 years were recruited from the seventh grade of primary schools in Telemark County, Norway. Parents gave information about mental health and peer problems by completing the extended version of the Strength and Difficulties Questionnaire (SDQ). Height and weight were objectively measured. Complete data were obtained for 744 children. Fisher’s exact probability test and multiple logistic regressions were used. Most children had normal good mental health. Multiple logistic regression analysis showed that overweight children were more likely to have indications of psychiatric disorders (adjusted OR: 1.8, CI: 1.0–3.2) and peer problems (adjusted OR: 2.6, CI: 1.6–4.2) than normal-weight children, when adjusted for relevant background variables. When adjusted for peer problems, the association between overweight and indications of any psychiatric disorder was no longer significant. The results support the hypothesis that peer problems may be an important underlying factor for mental health problems in overweight children.
KeywordsOverweight Peer problems Mental health Psychiatric disorder Children Adolescents
Overweight and mental health problems in children and adolescents are two major health challenges in Norway, as well as in other western countries . Being overweight in childhood may have adverse consequences on physical morbidity in adulthood and result in premature mortality. Furthermore, common mental disorders seen in adulthood often emerge first in childhood and adolescence. Approximately half of all lifetime mental disorders start by the mid-teens . This highlights the importance of early prevention and intervention.
A substantial increase in overweight has been observed in Norwegian school children over the last 30 years [3, 4]. Furthermore, it is estimated that 15–20 % of all Norwegian children and adolescents have reduced functioning due to symptoms of mental disorders, and approximately half of them will have such severe symptoms that they will meet the requirements for a psychiatric diagnosis . One study found that 7 % of 8–10-year-old Norwegian children met the criteria of any DSM-IV psychiatric disorder . The incidence increases with age, and is higher among adolescents .
In adult population studies, an association between psychopathology and obesity is often found . However, results from population-based studies of children and adolescents are conflicting [8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22]. Overweight and obese children have been shown to be at higher risk of poor psychological health in general [18, 20] internalizing and externalizing mental health problems , behavior problems  and of meeting the criteria for an ADHD diagnosis . Other studies, however, do not confirm such associations between overweight and mental health problems, or find the associations dependent of sociodemographic variables, lifestyle factors, or body-weight perceptions [9, 10, 12, 13, 14, 15, 16, 17, 19, 21].
The association between overweight and mental health problems is more often found in clinical groups of children than in population studies [23, 24, 25]. Elevated levels of psychopathology have also been reported among treatment-seeking obese Norwegian children and adolescents, when compared with a matched community sample . In a recently published review, Russell-Mayhew et al.  discuss and summarize the conflicting evidence in this field. They conclude that little is known about the relationship between mental health and childhood obesity, although there appears to be some consensus that obesity is a potential risk factor for psychological and emotional well-being in children and adolescents.
Weight-based stigmatization and negative attitudes to overweight children and adolescents are well documented . In a recently published comprehensive review, Puhl and King  further concluded that weight-based victimization may have serious consequences for the emotional, social, academic, and physical well-being of adolescents. Difficulties in peer relations are often observed among overweight children and adolescents. Overweight adolescents are more likely to be socially isolated [13, 30, 31], less accepted by peers , and experience victimization by peers more often than normal-weight adolescents [32, 33, 34]. They also report more difficulties in making friends . Peer problems, as a possible result of the social stigma attached to overweight, have been hypothesized to be an important underlying factor for mental health problems in overweight children and adolescents [27, 32]. More studies would be useful to explore the role of peer problems as a possible mediating variable  in the association between overweight and mental health problems.
Investigate the associations between overweight problems, peer problems, and indications of mental health problems in a sample of 12–13-year-old Norwegian school children.
Test the hypothesis that an association between overweight and mental health problems is mediated by peer problems.
Study design and sample
The present data were obtained from a study of primary school pupils in Telemark County, Norway. Data collection took place in the spring of 2010, when the children were in primary school grade 7 (age 12–13). The detailed data collection methods have been described previously [37, 38, 39]. All 104 primary schools in Telemark County were invited to participate in the study. In total, written parental consent for inclusion in the study was received for 1,095 out of 1,503 invited children (73 %), representing about half of the county’s seventh grade pupils. Data on mental health and peer problems were obtained for 871 pupils. Complete data, including weight and height measurements, were obtained for 744 children.
The research was conducted in accordance with the guidelines laid down in the Declaration of Helsinki and approved by the Regional Committee for Ethics in Medical Research and the Norwegian Data Inspectorate. Informed written consent was obtained from the parents of all participating children.
Strength and Difficulties Questionnaire
The children’s mental health problems, peer relation problems, and social competence were measured using the parental version of the extended Strength and Difficulties Questionnaire (SDQ) [37, 40]. The SDQ is a 25 item screening questionnaire for assessing mental health problems in children and adolescents aged 4–16 years. Four subscales, each with five items, cover emotional symptoms, conduct problems, hyperactivity, and peer problems. The emotional symptoms scale covers problems such as having many worries or fears, and complaints of headaches. The conduct problem scale covers problems such as having a hot temper, fighting, lying or cheating. The hyperactivity scale covers symptoms such as being overactive, impulsive and easily distracted. Peer problems include whether the child tends to play alone, has friends, is generally liked by other children, gets on better with adults than other children, and is picked on or bullied by other children. A fifth subscale, also with five items, covers prosocial behavior, and asks whether the child is considerate of other people’s feelings, helpful and kind to younger children. The latter is a measure of the child’s ability to act prosocially, independent of the difficulties measured by the other subscales.
The extended SDQ includes an impact supplement, a scale that rates the extent to which the respondent thinks that the child’s problems have an impact on daily functioning. In our study, parents gave information on the SDQ, including the impact scale. Information from SDQ subscales and the SDQ impact supplement was combined according to a scoring algorithm given by Goodman et al. . The algorithm makes separate predictions for indications of conduct-oppositional disorders, hyperactivity–inattention disorders and anxiety-depressive disorders, denominated in the following as “conduct disorders,” “hyperactivity,” and “emotional disorders,” respectively. These three subscales are combined to generate an overall prediction of indications of “any psychiatric disorder.” In the present study, we use “mental health problems” as an overall term to denominate the indications of all psychiatric disorders explained by the algorithm. The peer problems scale and prosocial behavior scale were not included in the scale predicting indications of any psychiatric disorder.
We combined the “possible” and “likely” categories into “possible/likely” and all comparisons were made between the “unlikely” group and the “possible/likely” group. The algorithm requires at least two informants (for example, parent and teacher) to meet the criteria of “likely” on the hyperactivity–inattention scale. As only information from parents (reporting together) was available, an adjustment was made to allow for the category “possible/likely” with one informant when the information gave a score within the defined “possible/likely” category range.
The weight and height of the children were measured in private by public health nurses at each school. The health nurses, using their professional judgment, decided how much of the measurement information was given to the child. The children were weighed wearing light clothing (i.e., trousers, T-shirt, socks), using calibrated, electronic scales measuring in 100 g increments. The BMI (kg/m2) of each child was calculated on the basis of the measurements. Child BMI categories were calculated using international obesity task force (IOTF) cutoff points (underweight, normal weight, overweight, obese), based on growth curves and BMIs of 17, 25 and 30 kg/m2 at age 18 [42, 43]. Because of small numbers, we included underweight children in the normal-weight group and obese children in the overweight group.
In addition to providing information about the mental health of their child, the parents answered questions about their own educational level and family income.
Parental educational levels were divided into three categories: “primary and lower secondary education” (10 years or less), “upper secondary education” (3–4 years of secondary education), and “university or university college.”
Family income was also divided into three categories: “both parents <Norwegian kroner (NOK) 300,000,” “one parent ≥NOK 300,000,” and “both parents ≥NOK 300,000.” (NOK 300,000 = EUR 40,849 as on 12 December 2012).
The bivariate associations between BMI categories, mental health problems, peer problems and social behavior problems were tested using Fisher’s exact test.
We used multiple logistic regression analysis to examine the association between BMI categories (independent variable), peer problems, and indications of any psychiatric disorder (dependent variables). Adjusted odds ratios (OR) and 95 % confidence intervals (CI) were calculated for risk of having indications of any psychiatric disorder and peer problems. The potential confounding background variables available for the multiple regression models were: maternal education, paternal education, family income, and child gender. We applied forward conditional selection and included variables significantly associated with the risk of having any psychiatric disorder or peer problems in the respective models (1a, 1b, 2a, 2b, and 3). Model 3 was also adjusted for peer problems.
For all tests, a significance level of p < 0.05 was applied. The questionnaires were scanned by Eyes and Hands (Readsoft Forms, Helsingborg, Sweden). Statistical analyses were performed using programs available in SPSS for Windows (version 19.0).
The results are based on the 744 children for whom complete parental reported data on mental health information and objectively measured height and weight were obtained. Of the participants, 52 % were girls and 48 % were boys. Some 49 % of mothers and 36 % of fathers were registered in the highest education category “university or university college,” 34 % of mothers and 42 % of fathers fell into the category “upper secondary education,” and 12 % of mothers and 12 % of fathers fell into the lowest education category, “primary/lower secondary education.” In total, 86 % of the parents were registered in the two highest categories of family income. Seventeen percent of the children were categorized as overweight (14 % overweight, 3 % obese).
Mental health problems, peer problems, and prosocial behavior problems of 12–13-year-old children according to the extended SDQ (n = 744)
Mental health problems, peer problems, and prosocial behavior problems
Indications of any psychiatric disordera
Indications of emotional disordersa
Indications of conduct disordersa
Indications of hyperactivity disordersa
Prosocial behavior problems
Prevalence of mental health problems, peer problems, and prosocial behavior problems by BMI categories (n = 744)
n (%) of Parents reporting possible or likely disorders/problems
Indications of any psychiatric disorder
Indications of emotional disorders
Indications of conduct disorders
Indications of hyperactivity disorders
Prosocial behavior problems
Associations between BMI categories and peer problems, and between BMI categories and indications of any psychiatric disorder (n = 744)
Total (n = 744)
Indications of any psychiatric disorder
Model 1a OR crude (95 % CI)
Model 2a OR adjusteda (95 % CI)
Model 1b OR crude (95 % CI)
Model 2b OR adjustedb (95 % CI)
Model 3 OR adjustedc (95 % CI)
In the present study, we observed that overweight children were more likely to have peer problems and mental health problems than normal-weight children. We found a significant association between overweight and mental health problems dependent on the presence of peer problems, supporting our hypothesis that the relation between overweight and mental health might be explained by peer problems as a mediating variable. All associations were observed independently of available background variables.
Other studies have used different assessments of mental health problems and peer relations, making direct comparison with our results difficult. However, some similarities can be observed. Our results are in line with several previous studies from Europe, Canada and the US in which overweight children and adolescents have been found to experience problematic peer relations or been subject to peer victimization. Overweight children have been found more likely to be socially isolated , and described as more socially withdrawn and found less attractive than others by their peers . In addition, parents of overweight adolescents more often reported that their youngster was withdrawn or did not get along with others than did other parents . Several studies addressing social relations have found overweight children and adolescents more often subject to peer victimization than children of normal weight [13, 32, 33, 34]. Overweight has been reported by peers to be a primary reason for youngsters being victimized and teased in a mean way . One study reported that overweight youngsters were more likely to be cruel or mean to others . Obese and overweight adolescents more often reported difficulties making new friends than normal-weight children, and they also more often believed that others made negative comments about them .
Results from previous population studies addressing the relationship between overweight/obesity and mental health problems of children and adolescents are inconsistent. However, obesity is often perceived to be a potential risk factor for the psychological and emotional well-being of children and adolescents . The association we found between overweight and indications of psychiatric disorders is consistent with this notion, and supports previous studies in which an association between overweight and poor mental health has been reported. In contrast to other studies [8, 11, 22], we were not able to identify any significant associations between overweight and indications of more specific psychiatric disorders. The absence of significant associations between overweight and indications of emotional disorders, conduct disorders, and hyperactivity disorders may be due to the relatively low number of adolescents with such problems, which increases the probability of not detecting true associations that are present (type II errors). Further, mental health problems are known to increase during adolescence [2, 5]. Our participants are relatively young. The associations often found in the adult population  may, therefore, appear at a later age.
Several studies have questioned a casual or predictive relationship between overweight and mental health problems in the general adolescent population . Problematic peer relations are often found to be associated with psychological problems among children and adolescents  and a general association between peer problems and indications of any psychiatric disorder was also observed in our study. Peer problems have been hypothesized to be an important underlying factor for mental health problems in overweight children [27, 32]. The overweight adolescent will often have own concerns about weight and shape, and experience weight-based teasing and stigmatization by others. This substantiate the notion that peer problems may be a particularly important factor in the association between childhood overweight and mental health problems . Our findings support this, as the association between overweight and mental health problems was no longer found to be significant when peer problems were taken into consideration. This, along with the strong association found between peer problems and indications of any psychiatric disorder, supports the hypothesis that peer problems are a mediator in the association between overweight and mental health problems.
Strengths and limitations
Strengths of the present study are the relatively large number of informants, the acceptable response rate, and the use of objectively measured weight and height to calculate BMI. Another strength is the availability of information about sociodemographic variables considered relevant for BMI status and mental health variability. The use of the extended SDQ for measuring indications of psychiatric disorders should also be considered strength of this study. The inclusion of the impact scale increases the validity of the SDQ as a measure of mental health problems compared with instruments that only ask about symptoms . The SDQ has been widely used in Norwegian community studies [37, 46].
The study also has limitations that should be recognized. One limitation is the lack of cross-informant comparisons, which is recommended when using the SDQ . The algorithm used was primarily developed for use with multiple informants—parents, teachers, and adolescents—but has also been used with parents as the only informants [48, 49]. With one informant, parental ratings have previously been found to be a more reliable predictor of clinical status than children’s self-reports . Using British norms may have resulted in some underestimation of problems, as Norwegian studies generally report lower symptom scale means than British studies . These limitations mainly concern potential underestimation of SDQ difficulties scores, which in turn may have caused a weakening of the associations studied.
It is important to recognize that the SDQ peer problems subscale is a general scale that measures different aspects of peer relationships. One question specifically addresses peer victimization, but the scale also includes questions related to social withdrawal and whether the child is generally liked by other children. The broad nature of the scale limits the ability to study specific aspects of peer problems in detail. However, for our purpose, a scale covering several aspects of peer problems was preferable. Further studies are needed to provide detailed knowledge of how different aspects of peer problems may influence the mental health of overweight children.
In our study, obesity and overweight were defined as one category. The study did not include enough obese children to investigate obesity separately. However, we find it likely that the associations observed would be even stronger in obese children. We used age- and sex-adjusted BMI, which is a crude measure of overweight. Only data on height and weight were collected and available for the analysis and for our purpose, we considered BMI to be an acceptable measure of overweight.
One possible limitation of the results is bias due to non responders. We included only participants with complete data on BMI categories and mental health variables in the analyses. Because those with missing data on these variables did not differ substantially from the remaining informants with regard to background variables, we consider this problem to be limited. Data collection was limited to one Norwegian county, and the participating parents had a somewhat higher educational level and total family income than the county’s population in general. The results are therefore not necessarily representative of the national population. Although the analyses were adjusted for several possible confounders, other biological and environmental factors not taken into account here may have attenuated the associations observed between overweight, peer problems, and indications of mental health problems.
The study’s cross-sectional design eliminates the possibility of identifying causal relationships. Furthermore, the associations found may be bidirectional, implying that mental health problems or peer problems may promote comfort eating and weight gain. Adolescents who feel sad and depressed because of weight-based victimization might increase food consumption as a self-soothing behavior [51, 52]. To clarify the direction of the associations observed, longitudinal studies are needed. As we plan to repeat the data collection after 3 years, we hope to present longitudinal data to clarify the direction of the associations observed.
An understanding of mental health problems among children and adolescents is important in targeting public health activities and clinical practice. Our findings support the hypothesis that peer problems may play an important role for the mental health of overweight children. To reduce mental health problems among overweight children and adolescents, negative attitudes and stereotypes toward overweight children should be addressed. Further longitudinal studies are needed to provide detailed knowledge of how different aspects of peer problems are related to mental health problems among overweight and obese children, and to clarify the direction of the associations observed. The results highlight the importance of reducing stigmatization of this vulnerable group.
This research was supported by Telemark University College, Telemark Hospital, the Research Council of Norway, and the Public Health Programme for Telemark. The authors appreciate the cooperation of the children and their parents, the faculty and staff of the Telemark County primary and lower secondary schools, and the public health nurses who participated in this study.
Conflict of interest
All authors declare that they have no conflicts of interest.
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