I have PT scores and records for the bulk of my career. There is a discernable trend. Your scores and performance will drop, whether you train or not. Your hearing and eyesight will deteriorate too. By the time you reach 50 something, if you remain active, you will hurt, and may be hurt from injury and overuse. Count on it.
I will not forget the comments from one of our young lion types as the 50 yr olds recovered from a 1.5 mile run. When he learned that at HIS age several of us posted faster times than he did that day, he asked "What happened?"
Arrogant stupid fool. Life happened, age happened. You can forestall the aging process, but you cannot prevent it.