Wednesday, June 27, 2007

How does alcohol affect the mind?

It takes only minutes for the alcohol in a sip of beer, wine, or liquor to enter the bloodstream and reach the brain. There alcohol swiftly finds the neocortex, the area of the brain where, among much other activity, many of the signals that affect our social behavior are processed. Some of these signals apparently work to increase our caution and inhibit our gregariousness, raising our anxiety about interacting with people.
Somehow, alcohol counteracts the inhibiting signals in the neocortex, and one result is that people who feel self-conscious at a cocktail party find themselves loosening up after a drink. This may happen, according to one theory, because alcohol blocks the action of a neurotransmitter known as GABA, which is essential for creating anxiety messages in the neocortex.

After a typical drink's worth of alcohol, it takes the liver about an hour to break down the alcohol circulating in the bloodstream. Amounts in excess of roughly an ounce per hour build up in the bloodstream, resulting in more alcohol reaching the brain. The deeper interior parts of the brain are affected, causing sleepiness in some people and belligerence in others. One reason why alcohol produces belligerent behavior, a British study found, is that intoxicated people misread facial expressions. They get into fights because they perceive anger or contempt when none existed.

If the alcohol in the bloodstream exceeds a certain critical point, the brain stem, which governs such autonomic functions as breathing, can't function. Death by suffocation follows. This is called acute alcohol poisoning and there is no antidote for it.

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