Here's a little game that a buddy forwarded to me. I scored a 31 on my first attempt and a 23 on my second. Below are the instructions. So I guess my brain got 8 years younger in a matter of 10 minutes, according to this thing.
The site instructions are in Japanese, so read below
1. Click "Start"
2. You'll see a count down of 3,2,1 and then a series of number will flash
3. Memorize the number's position on the screen and then click the circle from where you remember seeing the "lowest" number to the "highest" number.
4. At the end of game, the computer will tell you the age of your brain.