I was reading the [television and cognitive decline](https://www.nature.com/articles/s41598-019-39354-4) thread and it got me thinking: what are the best (i.e. most efficient and proven effective) ways to improve cognition?It seems there are a lot of services out there that purport to provide some benefit, but I'm hoping some folks in this community can point to something true, even if it isn't necessarily fashionable.