Alz.org is the website for the US based Alzheimer’s Association. They focus primarily on Alzheimer’s, but also contain some material on other forms of dementia.
The site interface is designed to be easy to navigate for those who are not medical professionals, but digging through some of the menus will get you to refereed journal articles and other professional resources, as well as granular suggestions for caregivers seeking to offer dignified, appropriate levels of support for loved ones.
Of special interest: their phone hotline, available 24/7. From my experience, they seem to have a vast phone-tree of specialist consultants—so you can call in to vent, ask for tips and strategies, or to get pointed in the right direction for independent research.
I was especially impressed with their ability to get me connected to local resources—lists of adult daycare, nursing homes & memory care, checklists on how to evaluate offerings, and so on. So often, I’ve asked for help through insurance company reps, or doctors’ offices, or dug up stuff myself online—only to find it’s outdated or contains information that isn’t useful.