Buy into a brain training exercise programme, and you will be given time-consuming and difficult exercises to do. The harder you work, the more you will progress. You might even bring down your “brain age.” But you won’t actually be making yourself any cleverer. All you will be doing is wasting time, and making the authors of the brain training exercise programme richer.
You’d be much better off learning a new language, doing some physical exercise, or just sleeping for longer.
“A person who spends many hours on brain training games but never engages in any real-world challenges is like the karate pupil who has only ever performed solo exercises in the dojo. Woe betide they ever find themselves in a fight.”
N.B. The BPS research digest is brilliant, and just at the right level for A level students. Read it.