Cortical thinning in patients with late-life minor depression

Abstract

Objectives: Clinically significant minor depression is among the most common mental disorders in the elderly individuals and is associated with considerable medical and psychosocial morbidity. Despite its clinical impact, the biological basis of minor depression in the elderly individuals remains poorly understood. The purpose of our current study was to examine cortical thickness in a sample of patients with late-life minor depression and non-depressed comparison subjects using magnetic resonance imaging (MRI).

Design: Cross-sectional analysis.

Setting: Community.

Participants: Patients (n = 16; mean age = 76.2 ± 7.5) met modified DSM (Diagnostic and Statistical Manual of Mental Disorders) criteria for minor depression and were free of other brain diseases. Healthy comparison subjects (HC; n = 16) were of comparable age and gender distribution.

Measurements: All subjects were scanned on a 1.5-Tesla GE scanner and brain regions were outlined using Freesurfer Image Analysis.

Results: Results show that patients with minor depression have cortical thinning in the right cingulate cortex compared to HC.

Conclusions: These findings indicate that abnormalities in specific structures and associated neural circuitry may underlie minor and major depression in the elderly individuals and the pathophysiological abnormalities are comparable in major and less severe forms of the disorder.

Keywords: Freesurfer; MRI; minor depression.

Figure 1

Uncorrected voxel-wise thickness difference maps between healthy comparison and minor depression groups, with general linear model controlled for age and global thickness by hemisphere: (A) left lateral view (B) left medial view (C) right lateral view (D) right medial view. Areas of significant cortical thinning are indicated in blue while significant cortical thickening is indicated in red. The significance scale at the bottom of each view is represented as-log(p). Light gray band indicates a gyrus and dark gray sulcus. Cortical parcellation (color band) is overlaid on top of the surface with transparency on. The area of significant cortical thinning that survived permutation testing was the right isthmus cingulate cortex (white circle).

Figure 2

Scatterplot demonstrating significant cortical thinning in the right isthmus cingulate (p = .0037, F=10.03, df=1,28, adjusted p = .046)