I started out with my problem solving ability at 99.8%, As I wondered where I could go from here, I've found myself now at 85%. So did I lose brain power?
My memory, though, which had been at 50% rose to the 92% once I gave it more attention and effort.
To sum it, I've learned the games and improved my performance of them to the top of my age group by learning them. After a while some of them became boring. I skip them all the time (hence losing points?) Some others I've reached as high as I can (e.g. Trains at level 12) and all my failed efforts only lower my scores, not improve my brain ability.
For me, Lumosity is fun.