I've been playing games for 30+ years and can attest to this first hand. Sad thing is you don't really notice it as it's a gradual process. The font seems smaller and the rules more complicated as you go along. A decade ago I could put in a sports game or first person shooter and be aware of everything on the screen and react instantly. If playing Madden I could spot a blitz a mile away, scan field and dump it off to open receiver before defenders got anywhere near my quarterback. Call of Duty... I could spot a camper and snipe him on first shot without missing a stride. Now I'm getting sacked on a regular basis and walking into ambushes. It's not all downhill on a good day I get in the zone, turn back the hands of time and game with the best of them. Still those days are getting fewer by the year.
So why continue to game when at an disadvantage to the youth? Easy... we are gamers pure and simple. As long as it bring us happiness we will continue to play. The victories are twice as rewarding and it's a way to stick it to father time. Not to mention a little trash talking to guy we just beat half our age.