Below is another picture of an MRI of two brains. One is of a social (non-addicted) drinker’s brain. The other is of an alcoholic’s brain.  Each person was shown two pictures. First they were shown a picture of a chair… very non-threatening and generic, to get a baseline read.  Next they were shown a picture of a glass of beer.

As you can see, the social drinker’s brain registered no difference between the chair and the beer, which is “normal.”  But the alcoholic’s brain lit up in the area of the limbic system, sending “craving” and “seeking” signals immediately to the other parts of the brain.

http://www.enterhealth.com/faqs/why-alcohol-and-drug-a-brain-disease