Is it against the California state law for a person with Alzheimer's to live alone?

As an example, once the MD tells you "mom should not live alone" and you have POA, you are responsible. Some think it is OK to just lock mom in while they go to work. They get arrested for neglect if mom calls 911.
On the other hand if MD says she is doing fine, and she falls while you are out shopping, it is just an accident, no fault.
Alzheimer's has many stages. Early on the patient is fine alone.
Some states say they have to stop driving. California simply requires a driver be evaluated. Some pass, some fail .

I wouldn't blame you if you use it as a lever to get her out of her own home. Whether it is strictly true doesn't matter, it could work as long as she believes.
"Mom, if we don't get busy and pick somewhere nice and move you the government will stick you in the county home..."

What the person may have been referring to is family members allowing someone who is incompetent and unable to care for themselves to live alone. I suppose they could be charged with some kind of neglect, under certain circumstances. I can't imagine that the dementia patient would be charged.

You might consult with an attorney in that state to see what is required and if they are at risk of doing that. Also, they may ask about options. Like filing with the courts to be appointed Guardian. That way, the Guardian can make the decisions about the Ward, regardless of their wishes, if it's for the Ward's own protection.

Normally, Adult Protective Services may also look into the matter if a family member is concerned.

inthemiddle, at this point you have to tread lightly and provide oversight gently. What we did was get online access to her bank accounts to be sure she was paying her bills. We would ask "Oh did you get your bill for XXXX?" We went with her to MD appointments, let her do all the talking and silently shake our head "NO" if she told a fib. The MD was very alert and picked up on this immediately. We took her for the concerts or a free lunch at AL facilities. We said no not for now, but keep the one you like in mind for later. It worked.

asking because my mother in-law is probably stage 3, maybe 4 and lives alone. She will not leave her home, and it is impossible to move in with her. Was told recently that there are laws against letting her live alone, but could not find any on-line. If she gets hurt are her children liable?

Wow Pam wouldn't it be nice if HIPPA really worked!!!

Don't know the answer to that but in the very early stages I don't see why they should not. After all we all potentially have Alzheimers only some have been diagnosed. How would the State of California know? To add to that Alzheimers can only be correctly diagnosed after death. Other forms of dementia are more easily identified. Now where did I leave my head?

No, because the state has no access to your medical records under HIPAA. The state will step in only if you are a danger to yourself or others.
Under the Baker Act, a person found in that situation can be admitted to a hospital for psychiatric evaluation.