Hi wisflog, and thanks for your answer. I have had nearly the same advice from some of my MD's, but not all.
I believe that you are correct about the relationship between drinking and nutritional deficiency of B vitamins, particularly B1 (thiamine). However, there appears to be another form of PN caused by alcohol separate from the form related to vitamin deficiency, which is the direct toxic effect of alcohol on nerves. For example, read this paper: https://onlinelibrary.wiley.com/doi/abs/10.1002/ana.10550.
My quest is to find out what amount of alcohol is "safe". This probably seems silly to most of you, but being 74y/o, and finding many of my previous pleasures disappearing (some as a result of the PN, and some as the result of age), I'd hate to give up my evening martini if it makes no difference to my health (like your 95 y/o smoker.