A no of people seem to be making news of this, although it has to be said that there were rumours going around already.
It reminds me of Harold Wilson's last years. I remember being a teenager and seeing him and his wife on St Mary's, whilst on holiday in the Scilly Isles, and then wondering why he didn't appear in the news so much as other the former PM's (then Home, Heath, and Callaghan). I soon found out when I came across John Junor's memoirs where he alluded to Wilson's mental decline, and indeed in Wilson's last years the rumours did increase. It certainly explained why he quit early.
Now of course, his family and friends are now open about what appened, so is Carol Thatcher right to have mentioned her mother's condition.
Well I imagine as a next of kin, she may well know best and know more about the situation as to assess whether it is in the public interest. Plus Carol is no idiot and is well regarded by many people as her brother is disliked. So I suspect that now is not the time to cast judgement and to hope and pray that Baroness Thatcher gets as much help and support as she can get