Q: My mom has a lot of credit card debt. Are people who get in debt because of Alzheimer's disease liable?
A: Your question raises a difficult issue. A person who incurs a debt is considered legally responsible for the debt unless you can prove that she was not competent when she signed up for whatever it was that cost so much.
I would immediately seek legal advice as to whether you can get the debt waived, based on her inability to understand what she was doing when she got into this debt. It is possible to do so, but it will cost money for attorney's fees to help you. There may be reduced-fee attorneys available for this kind of matter through your county bar association, AARP's list of lower cost attorneys and through various other legal services organizations serving the elderly.
I suggest that you get moving immediately. There may be other problems besides the credit card debt. A review of all of mom's financial records is in order, and now.
A larger question is how the problem happened in the first place. If mom was developing dementia, it did not happen overnight. Family members must have known that mom had memory problems for quite some time before the debt issue came up. When any adult child notices that a parent has memory loss, it is important to persuade the elder to get to a doctor as soon as possible.
A diagnosis can be a warning that everyone needs to step up and take protective measures to prevent mom from doing foolish things with money, especially if finances are limited. Loss of the ability to understand money, do math or realize the consequences of placing orders or giving money to others can occur in the earliest stages of dementia. The elder may be able to live independently and seem pretty well, but dementia is a tragic and sneaky thief that steals ability invisibly. A person with dementia absolutely needs to plan ahead and appoint an agent on a durable power of attorney (DPOA) for finances to prevent the kind of nightmare debt you now have to deal with in the situation you describe.