There are new studies showing speeding up your brain's reaction time can help lower the risk of alzheimers and make you better at volleyball (ok the second part I added), but here are some links to help your reaction time.
Importance to children's brains: https://www.the-test-tutor.com/blogs/news/games-and-activities-to-improve-your-childs-processing-speed#:~:text=Games%20and%20Activities%20to%20Boost%20Processing%20Speed.%20Here,the%20faster%20they%20will%20become%20at%20using%20them.
Brain Games: https://braincurls.com/