Medial orbital frontal lesions in late-onset depression

Early studies using magnetic resonance (MR) imaging suggested that subcortical vascular changes are more prevalent in late-life depression and that they may play a role in the pathophysiology of depression. Studying the location of the lesion relative to the occurrence of depression could be critical in delineating the neuroanatomic substrates of depression. Our purpose was to characterize these lesions in terms of location by development of statistical parametric maps of lesions that differentiate patients from control subjects.

Magnetic resonance images were acquired on 88 elderly depressed subjects ("patients," unipolar major depression assessed using the Duke Depression Evaluation Schedule, age range 63-80 years) enrolled in the Duke University Clinical Research Center for the Study of Late-Life Depression and 47 age- and gender-matched nondepressed subjects ("control subjects"). The MR protocol includes a volumetric, dual-contrast fast spin-echo pulse sequence. A statistical parametric map was formed from a two-group t test to test for differences in lesion density between patients and control subjects. Additional testing was performed to evaluate whether there were regions that correlated with the severity of depression using the 17-item Hamilton Depression rating.

The statistical parametric mapping analysis between groups showed two major regions of increased lesion density in the patients in the medial orbital prefrontal white matter. Severity of depression among depressed patients was correlated with lesions in the medial orbital region.

This study supports recent evidence implicating the medial orbital frontal cortex in depression.