What causes this behavior?

These behaviors are simply a part of the dementia. No, your loved one is not going crazy. Their behavior is just a result of the underlying medical condition. 

Sure, the symptoms might be embarrassing, difficult to deal with, even on rare occasions dangerous—but they are symptoms of an illness just like any other medical condition.

And these behaviors are not at all uncommon. Of the 8 million Americans with dementia, 75% of them will experience these symptoms during the course of the disease.