My stepfather had Alzheimer's, passed away from complications after a fall in Feburary of this year. Just missing birthdays doesn't really indicate dementia to me, even in someone who normally wouldn't forget them. My Gram is almost 90 and has been forgetting a few more every years for probably 10 or more years. Otherwise her cognitive ability is pretty good (haven't tried math, but she was a food stamp auditor for years and tends to do everything with a calculator due to that), she drives very well during the day, pays her bills, lives alone, etc. About the only thing she can't really do anymore is take her little boats out on the river to fish, and that's mainly due to balance. She just fishes from her dock now.
Anyway, your mom sounds pretty normal to me, but if you start to see more, or other alarming signs, try to visit the doc with her, or call her doc and mention your concerns, so s/he is aware and can gently check into it at her next appt.
Sent from Petguide.com Free App