Brendan Koerner profiles AA:
As dependence grows, alcoholics also lose the ability to properly regulate their behavior. This regulation is the responsibility of the prefrontal cortex, which is charged with keeping the rest of the brain apprised of the consequences of harmful actions. But mind-altering substances slowly rob the cortex of so-called synaptic plasticity, which makes it harder for neurons to communicate with one another. When this happens, alcoholics become less likely to stop drinking, since their prefrontal cortex cannot effectively warn of the dangers of bad habits. This is why even though some people may be fully cognizant of the problems that result from drinking, they don't do anything to avoid them.
Jonah Lehrer takes a second look at the neurological mechanisms at play.