This is an interesting article, too. When the stress of caring for someone with dementia symptoms, you need to remember that their brain isn't functioning. The cells not communicating with one another. Higher level thinking skills, memory, language, are slowly affected.
The type of symptoms depends upon the cause of the dementia, but they follow patterns.
The agitation, that is common with many patients, can be disconcerting. I've had clients yell and swear at me, and you have to realize that their inhibitions are reduced.