Functional connectivity in late-life depression using resting-state functional magnetic resonance imaging.

OBJECTIVE: To investigate whether there are differences in brain connectivity in late-life depression (LLD) and nondepressed subjects using the left and right heads of caudate nuclei (hCN) as the seed regions.
DESIGN: Resting-state functional magnetic resonance imaging (fMRI) data were collected using a 3-Tesla MRI System.
SETTING: Subjects were recruited from primary or secondary care services in the Newcastle area. PARTICIPANTS: Thirty-three subjects aged 65 years and older; 16 who had a recent episode of LLD and 17 nondepressed subjects. MEASUREMENTS: Functional connectivity was analyzed by extracting the temporal signal variation from the left and right hCN and cross correlating with the rest of the brain.
RESULTS: Significant connectivity between the hCN and frontal areas was observed in the nondepressed group, whereas in LLD, connectivity was seen over a much wider area. Regions showing significantly greater connectivity (p < or =0.05) in LLD compared with the nondepressed group were frontal (precentral, subgyral, middle frontal, and paracentral lobule), sublobar (thalamus and insula), limbic (cingulate), parietal (postcentral gyrus, precuneus, inferior parietal lobule, and supramarginal gyrus), and temporal (superior temporal gyrus). Conversely, no brain regions showed greater connectivity in the nondepressed group than LLD. In both groups, the right hCN showed significantly greater connectivity than the left in numerous brain regions, but connectivity for the left hCN did not exceed the right in any brain regions.
CONCLUSIONS: This resting-state study showed increased connectivity in specific brain regions in LLD compared with the nondepressed group, which supports the view that functional connectivity is altered in depression.