This is a good idea. Anything that is going to help, even a little, with the lack of concentration, memory problems, mental dullness. It would be better if a definite cause could be found, chemotherapy? radiotherapy? depression? too early menopause?, until then keeping mentally active is helpful. In my own experience i have found it's improved some over time, but has not gone back to my former sharpness. i found reading difficult, so i started back with reading less complicated books for shorter periods. i also played some simple word-games (there are some on the offbeat forum here in Topix). Basically find a level of something which stimulates/taxes you but not overly so then gradually work a bit harder.