I was diagnosed at age 44 but I'd had it for several years for sure; maybe for decades mildly. I think there is too much to consider to make broad statements related to age alone. I'm 52 now and it's either mild RRMS or mild SPMS that I have. I don't get symptoms anymore like relapses but I still have the old stuff that hangs on. Hoping I don't get relapses anymore, anyway.