HIPPOCAMPAL VOLUME ALTERATIONS IN FIRST-EPISODE DRUG-NAIVE ADOLESCENTS WITH MDD AND SUICIDAL IDEATION

Abstract

Objectives MDD is a major health problem affecting children and adolescents worldwide. Alterations in various prefrontal and subcortical structures, especially the smaller hippocampus, have been associated with depression. Few studies have investigated the neural substrates of self-injurious behavior in adolescents with MDD. We aimed to examine the brain structural alteration in first-onset, drug-naïve adolescents with MDD exhibiting suicidal behaviors compared to healthy controls.

Methods The study investigated 30 adolescent patients with MDD and suicidal ideation and 27 age-matched healthy adolescents. FreeSurfer 6.0 was used to analyze image data. Hippocampal subfield volumes were extracted and normalized for intracranial volumes, and analyses were performed using t tests. Group differences between adolescents with MDD and healthy controls were analyzed by a general linear model using the General Linear Model (GLM) tool embedded in FreeSurfer, with age, gender, educational year, and IQ as covariates. Permutation-based cluster correction for multiple comparisons was performed.

Results A total of 30 first-episode, drug-naïve patients with MDD (mean age = 14.9 ± 1.5 years) and 27 healthy controls (mean age = 16.0 ± 1.0 years) were enrolled in the study. Patients with MDD were significantly younger, had higher Hamilton Depression Rating Scale (HDRS) scores and lower IQ than controls. There were no significant differences in normalized volumes of the total intracranial volume nor other hippocampal subfields between groups. Group analysis using general linear model yielded no significant change in cortical thickness or subcortical volume in the MDD group compared with healthy controls. Compared to controls, patients had significant hippocampal volume reductions ( F 1,55 = 2.687; p = 0.047).

Conclusions Our result suggests that suicidal adolescents with MDD exhibit significant volume reduction in the hippocampus compared to healthy controls. Our results replicate and extend the existing findings on the hippocampal volume reductions in patients with MDD, focusing specifically on adolescent, suicidal patients with MDD. Future neuroimaging studies involving larger and more generalizable samples will be helpful to further elucidate the pathophysiology and neurobiology underlying adolescent depression.