Amplitude of low-frequency fluctuation (ALFF) alterations in adults with subthreshold depression after physical exercise: A resting-state fMRI study

Background: Physical exercise has been proved to reduce the risk of major depression in Subthreshold depression (StD) individuals effectively, yet little is known about the spontaneous brain activity changes associated with physical exercise. Methods: A total of 70 adult subjects, including 38 StD and 32 healthy control (HC) subjects, underwent a resting-state functional magnetic resonance imaging (rs-fMRI) before and after eight-week aerobic exercise respectively. Then, the amplitude of low-frequency fluctuation (ALFF) alterations between the two groups were quantitatively analyzed. Results: Before exercise intervention, the rs-fMRI data showed increased ALFF of the right putamen in the StD group compared with HC group. After exercise intervention, there was no significant ALFF change observed between the StD and HC groups. The longitudinal ALFF differences from pre- to post-exercise intervention showed significantly decreased ALFF in the right middle and inferior occipital gyrus, right middle and inferior temporal gyrus, right fusiform gyrus (FG), while increased ALFF in the right middle cingulate, right superior parietal louble, right inferior parietal lobule (IPL) (inferior parietal gyrus and supramarginal gyrus), and bilateral precuneus in the StD group. As for HC group, the results showed that decreased ALFF in the right FG and right parahippocampus, while increased ALFF in the right precuneus, right middle cingulate, right supplementary motor area, right superior parietal lobule and right paracentral lobule in the HC group. No significant correlation between changes of ALFF and clinical scale scores in the StD group. Limitations: The definitions of StD are varied in terms of different studies, the final sample size was relatively small, and the age range of the subjects in this study was narrow. Meanwhile, the exercise intervention trial was short-term. Conclusions: These results further support the standpoint that physical exercise has the potential to reshape the abnormal patterns of spontaneous brain activity in adults with StD.