Once an alcoholic starts drinking heavily, the mesolimbic pathway responds by cutting down its production of dopamine. Alcohol also messes with the balance between two other neurotransmitters: GABA and glutamate. Alcohol spurs the release of more GABA, which inhibits neural activity, and clamps down on glutamate, which stimulates the brain. Combined with a shortage of dopamine, this makes the reward system increasingly lethargic, so it becomes harder and harder to rouse into action. That’s why long-term boozers must knock back seven or eight whiskeys just to feel “normal.” And why little else in life brings hardcore alcoholics pleasure of any kind.
