Additionally, burst analysis depicted in Figure 5 identified the six most vigorous keywords at the onset of their citation surges: “physical exercise” with an intensity of 4.23, “stress” at 3.38, “major depression” at 2.62, “BDNF” at 2.43, “meta-analysis” at 2.57, and “functional connectivity” at 2.25. Here, BDNF is linked to major depressive disorder.