Will my Mum eventually fall victim to Alzheimer's?

Hi everyone,

I've asked a few questions in the past (and was able to see the first couple of answers but as silly as it may sound I don't know how to access them now to read what others might have replied!) but if you've come across my other questions you'd know that my 63/4 year old mum lives with my 83 yrs old dad who has dementia with Lewy bodies and parkinsons & Alzheimer's of course. I have managed to get him signed up for a day centre 4 days a week it gives her a break for 5 hours whenever he goes. I also brought in a cleaner once a week to help her out with hardwork around the house.
My mum is so very sharp and clever she's also very calm and patient. However, recently she seems to be quite forgetful (though I forget some similar things too- and I've always assumed as humans we tend to forget a few unimportant things every now and then!) but I can't help but worry about her- im almost paranoid that she might catch the disease! I keep sending her brain quizzes and fun activities to do- I know she's stressed sometimes but I'm doing all I can. I take care her out when he's at the day centre and sometimes she just prefers to rest at home and I respect her wishes. She's only in her early 60's I pray to God that she doesn't get Alzhimers because there's so much I hope to do for her- have any of you seen a pattern whereby if one person gets it the partner does too? Thanking you all so much