Resting-state functional connectivity in major depression: abnormally increased contributions from subgenual cingulate cortex and thalamus.

BACKGROUND: Positron emission tomography (PET) studies of major depression have revealed resting-state abnormalities in the prefrontal and cingulate cortices. Recently, fMRI has been adapted to examine connectivity within a specific resting-state neural network--the default-mode network--that includes medial prefrontal and anterior cingulate cortices. The goal of this study was to examine resting-state, default-mode network functional connectivity in subjects with major depression and in healthy controls. METHODS: Twenty-eight subjects with major depression and 20 healthy controls underwent 5-min fMRI scans while resting quietly. Independent component analysis was used to isolate the default-mode network in each subject. Group maps of the default-mode network were compared. A within-group analysis was performed in the depressed group to explore effects of depression refractoriness on functional connectivity. RESULTS: Resting-state subgenual cingulate and thalamic functional connectivity with the default-mode network were significantly greater in the depressed subjects. Within the depressed group, the length of the current depressive episode correlated positively with functional connectivity in the subgenual cingulate. CONCLUSIONS: This is the first study to explore default-mode functional connectivity in major depression. The findings provide cross-modality confirmation of PET studies demonstrating increased thalamic and subgenual cingulate activity in major depression. Further, the within-subject connectivity analysis employed here brings these previously isolated regions of hypermetabolism into the context of a disordered neural network. The correlation between refractoriness and subgenual cingulate functional connectivity within the network suggests that a quantitative, resting-state fMRI measure could be used to guide therapy in individual subjects.

Clinical and biological effects of mifepristone treatment for psychotic depression.

Psychotic major depression (PMD) is found to be a relatively common psychiatric condition that affects up to nearly 20% of patients with major depression. Previous studies by our group have shown rapid reversal of psychotic symptoms in some PMD patients treated with mifepristone, in addition to restoring a more normal afternoon cortisol release. The rationale for treating patients with PMD with a glucocorticosteroid receptor antagonist is further discussed. In total, 30 patients with PMD were treated with either 600 mg/day mifepristone or placebo for 8 days in a randomized double-blind manner. The Hamilton Depression Rating Scale (HDRS) and the Brief Psychiatric Rating Scale (BPRS) were administered at baseline and again after 8 days of treatment. Cortisol and ACTH were measured hourly from 1800 to 0900 at baseline and after 8 days of treatment. Significantly, more patients in the mifepristone group (seven of 15) showed a 50% or greater decline on the BPRS positive symptom subscale, an index of psychotic symptoms, as compared to the placebo group (two of 15). Patients who received mifepristone had lower HDRS and BPRS scores at study completion compared to those who received placebo, but these differences were not statistically significant. In addition, mifepristone significantly elevated cortisol and ACTH levels and steepened ascending slopes from 1800 to 0100 and from 0100 to 0900 as compared to placebo. Clinical and biological effects of mifepristone were comparable among males and females. Age was found to significantly and positively correlate with changes in cortisol and ACTH. These results suggest that short-term use of mifepristone may be effective in the treatment of PMD and may re-regulate the HPA axis. Additional blinded studies are warranted.