It's more than video games:

- Becoming pregnant reduces grey matter[0].

- Watching porn reduces grey matter[1].

- Heavy use of Facebook reduces grey matter[2].

- Tweeting while watching TV reduces grey matter[3]. etc etc etc.

[0] https://arstechnica.com/science/2016/12/pregnancy-brain-mean...

[1] http://www.iflscience.com/brain/researchers-find-association...

[2] http://www.sciencedirect.com/science/article/pii/S0166432817...

[3] https://www.fastcompany.com/3036198/people-who-jump-from-scr...