The association between obesity and hyperactivity/anxiety among elementary school students in Japan.

Background: We aimed to evaluate the association between hyperactivity/anxiety and obesity among elementary school students in Matsuyama City, Japan.

Methods: We conducted a cross-sectional study of all 46 elementary school students (24, 296 students) in Matsuyama City. The questionnaire included question items from the Strengths and Difficulties Questionnaire (SDQ), as well as questions about height and weight. The students were classified into two groups according to Rohrer index. After separating the data by gender, we examined the association between (1) obesity and hyperactivity, (2) obesity and anxiety, and (3) obesity and combination of hyperactivity and anxiety, by estimating relative risk using Poisson regression model. We also conducted stratified analyses to examine the effect modification by age groups and unbalance of diet on those associations. Moreover, we calculated relative excess risk due to the interaction (RERI) to examine whether there was an additive interaction between hyperactivity and anxiety.

Results: Sixteen thousand forty-eight students were included in the present analysis. The prevalence ratio (PR) of being obese in girls who had both hyperactivity and anxiety was higher compared to girls without those symptoms (PR = 1.80; 95% CI 1.04-3.13). There was no significant difference in the prevalence ratio for obesity in boys, whether they were hyperactive, anxious, or neither. RERI was 0.00 for boys and 0.18 for girls.

Conclusion: We found a significant association between obesity and co-existence of hyperactivity and anxiety among elementary school girls. Our findings strengthen the need to further explore the association between childhood obesity, hyperactivity, and anxiety.