My sister 5 years my senior was diagnosed with Dementia at about 55 and that was 7 years ago. Even 7 years ago leaving her alone wasn't wise. Now a coherent conversation isn't possible.
I am 71 and the last living member (youngest) of my family. All before me developed the disease in their early 70”s and succumbed completely with it by the age of 77. All were driving issues.
I now show early signs of that devil disease and have made many changes in my lifestyle .
1. Hired a great Tax and Trust lawyer to put all my eggs in a legal basket.
2. Elevated trusted employees to ownership positions.
3. Given power of attorney to my CEO. Who is a 30 year employee.
4. Given the president a large position in the stock.
5. Set up trust so my wife will have “no problems”
6. Last but not least.. Purchased a Prius and had it programed to “go home” plus all places I normally go during the day. Put in effect a Sat. tracker..... Nice
I think your analysis is spot on. If just beer, even if he was very drunk, he would have sobered up in less than 5 days. I think he’s got something mental going on - probably early onset Alzheimers or dementia. While family/friends may not have noticed while he was at home/work, once he had a few beers and was in an unfamiliar place with lots of people/confusion going on, it exacerbated his condition. His family should take this as a serious issue and have him evaluated. I had an uncle (now deceased) with Alzheimers/dementia and this sounds a lot like some of his early ‘episodes’.