This is not like him. He claims to have only one drink, but we know this is not true. He may be forgettimg, but he is also sneaking it so it is not just a memory provlem.
My Mom did the same thing with alcohol. Throughout life, she never drank on a daily basis but would buy a case of beer maybe twice a year just to enjoy something different. As time passed, I noted that the occasional case became a once-per-month case...then a twice-per-month case...until finally she, alone, was drinking a case of 30 cans of beer PER WEEK! Like you, I was seeing a big difference in her personality & ability to function whenever she drank alcohol. After about 6 months of the 30 cans per week, she asked me to drop a payment off at her eye doctor since I was headed right by there. When the receptionist mentioned Mom was "turned around" during her last visit & wasn't sure how to get there or head back home, I went directly home, took Mom's keys, her license & her car & have not allowed her to drive since. Up until that day, I had no way to curtail her alcohol consumption while she was independent enough to drive herself to town & make her own purchases. Unfortunately, you may end up having to do what I did...put up with the alcohol abuse until he's unable to make his own purchases. Looking back, the dramatic increase in alcohol consumption occurred during her late-mild to early-moderate changes...a period when she could no longer deny that there was something wrong & her memory was failing. Personally, I think the alcohol thing is a combination problem...25% forgetting they already had one & 75% needing to 'dull' the anxiety of losing their memory & their independence.
Sometimes people self medicate and perhaps that's what he is trying to do. Does the alcohol seem to sedate him or agitate him? I would put aside trying to be sensitive. I would just focus on your parent's well being. The combination of dementia, alcohol and driving is extremely risky and I would try to intervene in some way on that. You may need to discuss this with his doctor. Maybe his doctor can make some recommendations.
I would also be concerned about your mother. Being in the house all the time with a dementia patient who is drinking considerable amounts of alcohol has to be unsettling. Perhaps a candid discussion with her about what is really going on with him might be helpful. Often seniors downplay or deny decline, but if you really look at how they are functioning, you see that it's not as they pretend.
Thanks for the reply...he is 83 years old, no prior abuse of alcohol. Just the daily ritual of a drink (scotch) before supper. He lives at home with my mother who is understandably distressed at this change of behavior. He does atill drive and pours his own drinks. He has started to drink other things when his scotch runs out, and is in denial about the amounts he is consuming. He is not himself when he drinks too much - not abusive, but unreasonable. He seems to have moments, days, of realization where he tones it down, but it doesn't last too long. If he wasn't sneaking it I would put it down to not being able to remember from drink to drink.
This is going to be difficult if he he can still drive, replenish his supply, hide bottles and sneak drinks. I don't know of any "sensitive" solution. His lack of reasoning could be a combination of dementia and alcohol, which is not good. My only thought is to intervene in some way, either directly or covertly. My Dad has mild dementia, still drives but he is not a drinker. But Mom and I do lots of constructive fibbing in order to get things done like carpet cleaning or to get him to let us spend money on caregivers or home repairs. He thinks he just fine and everything in the house is fine. It's not and we have to be very crafty with him. Your Dad may still be too high functioning but it's something to consider.
I would also be concerned about your mother. Being in the house all the time with a dementia patient who is drinking considerable amounts of alcohol has to be unsettling. Perhaps a candid discussion with her about what is really going on with him might be helpful. Often seniors downplay or deny decline, but if you really look at how they are functioning, you see that it's not as they pretend.
Depending on his level of dementia it may be possible to use some constructive deceit. Would he know the difference between non alcohol beer and wine?