INTRODUCTION

The prevalence of obesity in children and adolescents is increasing world-wide, notably in developing countries.[1, 2, 3, 4] Now-a-days, this problem has become one of the important concerns about general health at the global level.[5] Excess weight is associated with several adverse physical and mental health effects.[5, 6, 7, 8, 9]

Obesity in childhood and adolescence has different effects on mental health, including symptoms of anxiety, depression, insomnia, social isolation etc., In turn, these conditions would have negative consequences on social relationships and learning issues.[7, 10, 11] Some studies documented higher prevalence of mental disorders as depression and anxiety in obese than in normal-weight individuals.[12, 13] In contrast, the prevalence of mental disorders is increasing in children around the world; this can be due to the escalating trend of childhood obesity.[14, 15]

Due to the importance of mental health, it is considered as part of the World Health Organization Global School-based Health Survey (WHO-GSHS).[16] Similar to most other developing countries, Iran is facing double burden of nutritional disorders.[17, 18, 19, 20, 21] Some studies in Iran have considered the relationship of overweight and obesity with mental disorders.[16, 19, 20] Although most studies in Western countries found a higher prevalence of psychiatric disorders in overweight children and adolescents, but studies conducted in two cities in Iran did not document the relationship of body mass index (BMI) with depression and anxiety in Iranian students.[16, 20] Because of diversity in the cultural and socioeconomic background in different regions of Iran, it is necessary to extrapolate such investigations in different parts of the country to help in designing and implementing health promotion programs.

This nationwide study aims to assess the relationship of excess weight with some mental disorders in Iranian students by using the WHO-GSHS questionnaire.

METHODS

This nationwide cross-sectional study was conducted as part of the third national survey of a school-based surveillance system[21] entitled the Childhood and Adolescence Surveillance and PreventIon of Adult Non-communicable disease-III study.

National regulatory organizations and institutional ethical and scientific review boards approved the study. After explanation of the study aims and methods, verbal assent was obtained from students and written informed consent from their parents.

This study was conducted in 2009-2010 among 5570 students, aged range from 10 to 18 years. They were selected by random cluster sampling from urban and rural areas of 27 provinces in Iran. Detailed methodology is published previously.[22]

The WHO-GSHS questionnaire was used to assess the psychiatric distress of students. The questions related to the mental distress are presented in Appendix I.

Trained health professionals conducted the physical examination under standard protocols and by using calibrated instruments. BMI was calculated as weight (kg) divided by height squared (m²). BMI categories were defined according to the WHO reference curves.[23]

RESULTS

Data of 5528 students were complete for this study. Participants consisted of 2726 (49.7%) girls and 2802 (50.3%) boys. Their mean SD age was 14.7 (2.4) years, without significant difference in terms of gender. Overall 17.4% of participants were underweight, 7.9% were overweight and 8.8% were obese.

Table 1 shows the frequency of anxiety according to gender and BMI categories. According to their self-report, 3182 (58.7%) students had anxiety, which consisted of 1417 (53.1%) girls and 1765 (64.7%) boys. No significant association was documented neither between overweight and anxiety (odds ratio [OR]: 0.86, 95% confidence interval [CI]: 0.68-1.09), nor between obesity and anxiety (OR: 1.11, 95% CI: 0.88-1.40).

Table 1. Frequency of self-reported anxiety among Iranian adolescents by gender and weight status: The CASPIAN-III study

As can be seen in Table 2, 3389 (62.6%) of students reported to have depression, they consisted of 1643 (61.1%) girls and 1746 (64.3%) boys reported to have depression. There was no significant relationship between overweight and depression (OR: 1.11, 95% CI: 0.86-1.43) and between an obesity and depression (OR: 1.01, 95% CI: 0.79-1.29). The self-reported frequency of insomnia among students is presented in Table 3. It shows that 2618 (49.4%) of students consisting of 1285 (49.1%) girls and 1333 (49.7%) boys had insomnia. No significant relationship was found neither between overweight and insomnia (OR: 1.17, 95% CI:, 0.91-1.51), nor between obesity and insomnia (OR: 0.91, 95% CI: 0.71-1.17).

Table 2. Frequency of self-reported depression among Iranian students by gender and weight status: The CASPIAN-III study

Table 3. Frequency of self-reported insomnia among Iranian students by gender and weight status: The CASPIAN-III study

DISCUSSION

This study, which is the first nationwide study of its kind in Iran, showed that overweight and obesity were not associated with depression, anxiety and insomnia in Iranian adolescents. These findings are consistent with two previous studies on small sample size in Iran.[16, 20] Contrary to our findings, several studies in Western countries have documented higher prevalence of these mental disorders in overweight and obese individuals.[13, 24, 25, 26, 27] These differences could be because of social and cultural differences, especially the attitude of friends, family members and the community to obesity and obese person in various societies. Similar to previous studies in Iran, our findings propose that overweight and obesity in adolescence are well-accepted by the community and therefore the overweight or obese person is not under pressure by parents and peers.[16, 20] Some previous studies[27, 28] have suggested that obese children, who are mocked by their friends, would experience some negative feelings including shame, isolation and depression. Moreover, these studies proposed that pressure and sneap imposed by parents is increased in overweight and children and adolescents. It is also suggested that depression might lead to unhealthy behaviors and in turn might result in overweight and obesity.[29]

The current study showed that anxiety and depression are more prevalent in boys than in girls. Some previous studies reported higher prevalence of such disorders in 12-18-year old girls and 10-12-year old boys. They suggested that such differences might be because of hormonal changes during puberty.[16, 28] In another study, depression was reported to be more prevalent in girls with 15-18 years of age and boys aged 10-14 years.[30] Further studies shall be conducted about the effects of various items including genetic, environmental, cultural, social and nutritional factors on gender differences documented by various studies about the psychiatric distress during adolescence.

The present study did not find any significant difference in the prevalence of insomnia according to gender and weight status. Some studies documented higher prevalence of insomnia in girls and obese individuals.[24, 27] In our study, the prevalence of depression and anxiety was more than a previous study in Iran,[18] however, our finding is consistent with some other studies.[25, 26, 31]

Study limitations and strengths: The main limitations of this study are its cross-sectional setting and using self-reported data on psychiatric distress among adolescents. The main strengths are the novelty in the region, recruiting a large sample size of adolescents from diverse parts of the country, as well as using an internationally accepted questionnaire.

CONCLUSIONS

We did not find significant relationship between excess weight and psychological distress in Iranian students. This can be because of positive attitude of Iranian families toward fatness in childhood and adolescence.