There is a supplement called Senilife that might help. I seen some positive changes in my dog Bailey, not huge ones but maybe the longer they are on it the better it gets. The vet also suggested a quality fish oil supplement would be good too. 

Hi there ,

Dementia is an awful illness and just like humans our caninie buddys can get it and they share a lot of the human symptoms including something called sundowning which adds to confusion and agitation in the evening and at night..

In this article there are a few tips that can help to lessen the distress your dog is feeling..

https://www.scamperingpaws.com/seniors/sundowning-in-dogs.shtml

I hope this helps a little and good luck with Ruby I hope she feels a little more peaceful soon.

When my late German shepherd began having sundowners type symptons at 10, she was a wreck in the evening.  It was difficult for her and sad for me.

She had great results with a product I gave her the last two  and a half years of her life.

It is called Cholodin and is all natural.  Some vets sell it, but you can buy it on Amazon as well.  It doesn't work for all dogs, but may be worth a try.

I hope you find something that works.  I know firsthand how heartbreaking this can be.

We have had great success with CBD oil with our nineteen year old cat with dementia, though there are still nights when he sings at 3 a.m. until I go find him and tuck him into bed beside me.  I have heard of decent results with human anti-anxiety meds, too, from a close friend with an aged dog.  Good luck!