I don't know. Maybe. I mean, Alzheimer's sets in at 45, doesn't it? Also, arthritis! Asthma! Senility! Impotence! Your best bet is to become a couch potato for the rest of your life, that way you definitely won't be risking broken bones from jointlocks or passing out from strangleholds!
...I am just joking, don't get offended. Consult a physician before you start, and get your ass in shape. Jiujitsu is a mountain with no peak, but you can do it.