“…Most of existing studies conclude that there is a linear relationship between income and mental health, which is proved to be positive in both earlier studies (e.g., Diener et al, 1993;Marks and Fleming, 1999;Graham et al, 2004;Judge et al, 2010;Lund et al, 2010;Sareen et al, 2011;Sun et al, 2011;De Neve and Oswald, 2012) and more recent ones (e.g., Arvind et al, 2019;Elwell-Sutton et al, 2019;Macchia et al, 2020;Ridley et al, 2020;Swift et al, 2020;Tran et al, 2020;Hertz-Palmor et al, 2021;Hynek et al, 2021;New York: UN Sustainable Development Solutions Network, 2021;Pan et al, 2021;Su et al, 2021;Thomson et al, 2021;Hajek et al, 2022;Shields-Zeeman and Smit, 2022;Thomson et al, 2022). The conclusion drawn in this paper that income has a U-shaped impact on depression is consistent with findings of these studies to some extent, because as income increases mental health improves within a certain range of income.…”