Background: Abnormalities in limbic structures have been implicated in major depressive disorder (MDD). Although MDD is as common in adolescence as in adulthood, few studies have examined youth near illness onset in order to determine the possible influence of atypical development on the pathophysiology of this disorder.
Methods: Hippocampal volumes were measured in 17 MDD subjects (age = 16.67 +/- 1.83 years [mean +/- SD]; range = 13 - 18 years) and 17 age- and sex-matched healthy controls (16.23 +/- 1.61 years [mean +/- SD]; 13 - 18 years) using magnetic resonance imaging (MRI).
Results: An analysis of covariance revealed a significant difference between MDD and control subjects (F = 8.66, df = 1, 29, P = 0.006). This was more strongly localized to the left hippocampus (P = 0.001) than the right hippocampus (P = 0.047).
Conclusions: Our findings provide new evidence of abnormalities in the hippocampus in early onset depression. However, our results should be considered preliminary given the small sample size studied.