It’s a subject of active debate within the field. There is some evidence that playing new games - by new I mean things that you haven’t done before - has what’s called a neuroprotective effect.
The story goes - and it’s important to state that this is just one hypothesis - that if you are good at learning new tasks, then as the brain degenerates, or if your brain degenerates from a disease such as Alzheimer’s or dementia, as the brain tissue functions less well you’re better at routing around that because you’ve been practising doing things in new ways before the deterioration set in.
https://www.youtube.com/embed/-qQh46cIrUA?wmode=opaque
So what the neuroprotective effect story says is that the progression of the dementia or the degeneration is not effected by you playing these games, but you can work around it better.
"We need to say that there’s no consensus at the moment among neuroscientists that that effect is there"
Now that’s one hypothesis and one story, and there are peer review papers that say that. It’s also fair to say that there are other papers that have failed to find that effect. So we need to say that there’s no consensus at the moment among neuroscientists that that effect is there. It’s a logically plausible story but the evidence isn’t clear.
What is clear is that keeping active and avoiding social isolation and stagnation is better for your health. There’s no doubt about that. If there is a link involving sudoko, what’s important to say is that you don’t keep doing the same thing for years and years and years.
https://www.youtube.com/embed/rNc7-R9kRkU?wmode=opaque
If there is an effect it would seem to be related to taking on new mental challenges and becoming good at new tasks, rather than doing the same exercises again and again.