My ex-wife has been diagnosed with early onset dementia complicated by alcoholism. Any advice?

What sort of advice are you seeking? It's impossible to stop an alcoholic from drinking if they themselves do not want to, or are in denial about the problem in the first place.

My husband is going to visit a good friend of his in hospice tomorrow who has days left to live. He's 50 and dying of alcoholic cirrhosis of the liver. He knew what was happening to him but chose to continue drinking.

You can't save your ex wife from herself, nor can you force her into care, or to stop drinking, or convince her the dementia will worsen the more she drinks. Especially if you don't have medical POA. She'll probably have to hurt herself and get rushed to the hospital before she'll be forced into Assisted Living. And even then it may not happen.

Wishing you the best of luck with a difficult situation

Unless she has assigned you as her PoA or you become her legal guardian, you have no power. If you harp on the topic every time you have a chance, she will dread talking to you and may cut you out completely. When many well-meaning people wanted to "talk to" my wayward son to straighten him out, after years of us (his parents) talking to him, I had to just politely inform them that if just talking to him would have worked, it would have worked a long time ago. There's just no magic thing to say to your ex. She has to come to the acceptance of her diagnosis and alcoholism in her own time, if ever. May you receive peace in your heart.

The first thing our neurologist said was “alcohol is toxic”. If you want to keep your brain you can’t drink. Talk to the doctor about medications to cease drinking. Also, is she drinking to calm anxiety or depression.

So I hope this information, even if not shared with family, WAS shared in diagnostic workup because there could be alcoholic encepholopathy involved, which would require different workup from dementia altogether.