Measurement matters in the association between early adolescent depressive symptoms and body mass index.

OBJECTIVE

The objectives of this study were to examine associations between depressive symptoms and body mass over 1 year during early adolescence and to assess how the associations might differ depending upon whether self-reported or directly measured height and weight were used.

METHOD

Participants were 446 sixth-grade Seattle students. Depressive symptoms were assessed using the Mood and Feelings Questionnaire. Regression models were used to examine whether baseline depression status was associated with 12-month body mass index (BMI; using self-reported height and weight) and whether baseline overweight status was associated with 12-month depressive symptom score. Analyses were rerun among a subsample (n=165) who had height and weight directly measured.

RESULTS

Using BMI derived from self-reported values, depressed males had a significantly lower BMI than nondepressed males, while depressed females had a significantly higher BMI than nondepressed females, after adjusting for covariates. Among a subsample using measured height and weight values, however, depression was no longer associated with BMI in either gender. Baseline overweight status did not predict 12-month depression score.

CONCLUSIONS

Observed associations between depression and subsequent BMI were explained by differential misclassification of self-reported height and weight by depression status and gender. Direct measurement of height and weight may be necessary to ensure validity in studies of adolescent depression and weight-related outcomes.