Evidence shows a direct correlation between blood alcohol and alcohol in the brain. Let's take a look at the process by starting with the alcohol itself. Wine, beer and hard liquor all contain alcohol, or more specifically, ethanol. In the fermentation process that produces beer and wine, enzymes found in yeast are used to break sugars down into ethanol, a smaller and simpler chemical. Although our human chemistry allows us to metabolize sugars in much the same way as yeast cells, we can't form alcohol during this process because we lack the crucial enzymes present in the lowly yeast.
Alcohol content varies among drinks.
If you examine the label on a bottle of wine, you'll find that the concentration never exceeds 14 percent. Yeast cells that ferment the sugar in grapes can't survive when the alcohol content rises beyond that level. You may have wondered about the bubbles in sparkling wines and champagnes. The bubbles are actually carbon dioxide, a byproduct of fermentation. At the time of bottling, fermentation is still taking place, and the gas hasn't been allowed to escape.