Question

"a british study involving more than 11,000 participants indicated that brain-training activities over a period of six weeks ________ subsequent performance of the practiced mental skills, and ________ overall cognitive fitness."

Answer 1

I would say "improved" and "boosted" would be the two words to fill in the respective two blanks with, in that order. From personal experience and even as an older person, I know that using one's brain for example to do freelance work keeps one's brain sharp