Altered resting-state functional connectivity of amygdala subregions in adults with subthreshold depression after aerobic exercise

Aerobic exercise has been proved to reduce the risk of major depression in subthreshold depression (StD) individuals effectively, yet previous studies ignored the different functions of amygdala subregions. In this study, 44 StD individuals and 34 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging before and after eight weeks of aerobic exercise respectively. Transverse and longitudinal analyses were conducted based on the seed-based functional connectivity (FC) analysis between amygdala subregions and the whole brain of the two groups. The transverse analyses showed that compared to HCs, StD individuals showed abnormal FC between the right dorsal amygdala (DA) and right superior frontal gyrus, the left medial amygdala (MA) and left gyrus rectus, right caudate, as well as the right ventrolateral amygdala (VA) and right angular gyrus before the exercise intervention, while increased FC between the right DA and left supramarginal gyrus after the exercise intervention. The longitudinal analysis showed decreased FC between the left DA and left caudate, left middle frontal gyrus, while increased FC between the right MA and posterior central gyrus in StD individuals after exercise intervention. As for HCs, the DA showed FC differences with the insula, frontal lobe, parietal lobe, temporal lobe and thalamus. The MA showed FC differences with the central posterior gyrus, occipital lobe and thalamus. The VA showed FC differences with the calcarine cortex and parietal lobe. The findings demonstrated the alleviative effect of aerobic exercise on depression from the perspective of brain function.