They found that those who swore in the company of other people had increased depression. What more, those same people also lost social support.
The study has its limitations, as the sample. Swearing by women has an adverse effect on their social support. Particularly, societal norms dictate that women shouldn’t swear. The same study performed with young men may produce another result.
Robbins, M., Focella, E., Kasle, S., López, A., Weihs, K., and Mehl, M. (2011). Naturalistically observed swearing, emotional support, and depressive symptoms in women coping with illness. Health Psychology DOI: 10.1037/a0023431