To not have any notable scandals or other personal hardships during or after Family Ties ended (even though, he did appear in Cool as Ice). On the other hand, we have:
*Meredith Baxter claiming that her husband, David Birney was abusive and she was an alcoholic (ironic considering the infamous "Say Uncle" episode with Tom Hanks has Elyse's drunk brother Ned). This was of course before her third divorce and her proclaiming to be a lesbian.

*Michael J. Fox's ordeal with Parkinson's disease.

*Justine Bateman claiming that she had an eating disorder. Like Meredith Baxter, Justine looks rather whethered and badly aged.

*Tina Yothers' own issues with her weight (she appeared on Celebrity Fit Club I think twice).

*Brian Bonsall's numerous run-ins with the law as an adult.

I haven't seen Justine Bateman lately, but I don't think Meredith Baxter looks "badly aged" for 63. Maybe by Hollywood standards she does, but not in the real world.

I do have to say that I think Meredith has not aged well. Yeah, she's 63, but I think her face looks way harder than that of the average 63 year old. Obviously, she has had quite a few hardships in her life so it's not like there isn't a reason for it. Just my opinion, though.