Altered local activity and functional connectivity of the anterior cingulate cortex in elderly individuals with subthreshold depression.

The anterior cingulate cortex (ACC) is recognized as a key structure in the pathogenesis of depression. This study aimed to investigate the resting-state regional activity and functional connectivity of the ACC in a community sample of elderly individuals with subthreshold depression (StD). We employed resting-state functional magnetic resonance imaging to acquire data from 19 elderly subjects with StD and 18 normal controls. We used a regional amplitude of low-frequency fluctuation (ALFF) analysis and a correlation-based functional connectivity (FC) approach to explore changes in local activity and remote connectivity of the ACC in StD. Compared to controls, the StD group demonstrated increased ALFF in the anterior portion of the dorsal ACC (adACC). The adACC also displayed increased FC with the dorsolateral prefrontal cortex and supplementary motor area and decreased FC with several subcortical regions. The FC levels of the adACC displayed a trending correlation with self-reported depressive symptoms. This study is the first to reveal the ACC changes in resting-state activity and connectivity in the elderly with StD, suggesting that altered ALFF/FC of the adACC is an important feature of StD.