It's Not Just About Neurons

Your question cannot have a black or white, 0 or 1 answer. What determines the qualifiers "heavy" or "moderate" is subjective and unable to be determined, at least not by me on this side of a computer screen. Ethyl alcohol effects one's entire body, not just brain cells. I do not know anything of your family history, your particular history, your age, weight, amount of alcohol consumed per day, predisposing medical problems, diet, physical condition, etc. Moreover, I am not a medical doctor, let alone one who specializes in alcoholism. But, if you are asking this question, you are evidencing some concern for your health. There is no singular "threshold" for every individual. The variables are too numerous to even consider. The body is an integrated series of systems. The liver, kidneys, bladder, heart, pancreas, and other organ systems are all affected by alcohol consumption, and the enzyme production of those organ systems, or their efficiency to filter and remove the toxic chemical affect each other as well as the brain itself. 

Yes, the amount of alcohol consumed is significant. Ethyl alcohol is a central nervous system depressant drug that suppresses heartbeat and respiration, and can simply kill a person outright from alcohol poisoning. But regular intake of alcohol in "moderate" amounts is certainly not going to contribute to health. Long term use of significant amounts of ethanol actually shrinks the brain in size. Preservation or 'pickling' might be useful for laboratory specimens, but definitely not recommended for an individual who does not want to court possible dementia early in life. There are a host of medical problems associated with "moderate" alcohol consumption, some of which involve the brain directly. Get a full medical work-up. Ask your physician to palpate your liver, have a blood panel checked for liver enzyme levels and tests associated with drinking. Ask your physician this same question to get a medical doctor's opinion!

.