To investigate if there is an association between Body Mass Index and depression and if an association can be seen with age of menarche, anaemia and depression in Mexican adolescent girls 12-19 years old.

In the past decade, the number of deaths and disability-adjusted life years lost among adolescents has been continuously increasing, predominantly in low- middle income countries (LMIC’s). Results of recent studies have concluded that mental health disorders such as depression are responsible for a large percentage of these deaths, with reports highest in females. Unfortunately, causality is lacking. Concrete evidence exists that body mass index (BMI), anaemia and age of menarche (AAM) are risk factors for depression. The main aim of this study was to investigate if there is an association between BMI and depression in Mexican adolescent girls aged 12-19 years. In this descriptive cross-sectional study, 347 pubescent girls aged 12-19 years were recruited from six schools based in Santa Catarina and Monterrey as part of the Ten2Twenty study. BMI was determined by measuring and recording weight and height. Haemoglobin concentrations (Hb) were measured via Hemocue 201+ to determine the presence of anaemia. Socio-demographic and pubertal questionnaires were self- administered along with a survey sent via email on substance use. The presence of depressive symptoms (DS) was determined by interview and accompanying questionnaire. Cox regression was used to analyse the association between nutritional indicators and DS. The study population consisted of 347 adolescents aged 12-19 years with an average age 15.05(±1.9) years. 343 participants were included in the analysis as 4 were missing from the depression questionnaire. There is a weak but significant association between low Hb concentrations (<12.0g/dL) and depressive symptoms PR 0.8 (95% CI 0.7- 0.9). No association was found between BMI, AAM and depression. In Mexican adolescent girls, younger age is associated with an increased risk of DS. In addition, increasing Hb displayed a protective effect on the risk of DS, suggesting anaemia is a risk factor for DS. Further research is needed to assess the presence of iron-deficiency anaemia (IDA) and diagnose depression. Results further stress the necessity of interventions for adolescent girls with DS, particularly at ages 13+.