In Norman Doidge's first book 'The Brain That Heals Itself' he talks about brain exercises developed to work on brain plasticity. These exercises have undergone much research, putting them ahead of other brain exercises in cognitive enhancement, especially memory. One research study also found they reduced falls and benefited gait, though their research looks at 'normal population'. Another project found the games increased neurotrophic factors, the protein that heals the brain. I've been playing them for three months now, at 30-60 minutes a day. I know I'm thinking quicker and talking quicker. At social gatherings I find myself being witty again! The website brainhq.com offers free games, though you pay a subscription to open up all. Each game cleverly adjusts to your ability becoming harder while you are getting it right and becoming easier when you go wrong. Norman Doidge is strongly of the belief that they are excellent for people with all sorts of neurological deficits, particularly before the cognition deficit is diagnosable. There is even a suggestion that playing the games could slow the progression of PD.