A recent study of how alcohol affects the brain shows that it damages the very parts that are most needed for people to control their drinking behavior. And the more people drink, the worse the damage gets.

While it's not news that alcohol damages the brain, the study from Harvard Medical School was able to pinpoint the damage much more precisely than past studies. Previous studies were only able to show effects on large portions of the brain.

One reason that alcohol abuse is so difficult to treat: it damages the specific neural systems that are needed for drinkers to abstain from or curb their drinking.

By using high-resolution magnetic imaging scans, the Harvard researchers were able to compare structural differences in brain areas as small as a tenth of a millimeter. The researchers chiefly focused on the cerebral cortex, the area of the brain responsible for all higher functions of human cognition.

Scans of 31 individuals with a history of alcohol abuse (currently abstinent) were compared to those of 34 non-drinkers. The scans revealed marked differences in the thickness of several areas of the cerebral cortex.

Former drinkers all showed reduced thickness (atrophy) in seven different areas of the cerebral cortex. The most severe atrophy was in the frontal and temporal lobes, areas critical to learning and impulse control. And the atrophy was largest in those who had a greater history of alcohol abuse: the more they drank, the more severe was their brain damage.

Damage to the frontal lobe of the cerebral cortex can lead to changes in personality and behavior. These include difficulties in self-control and planning, reasoning, attention span and the ability to alter behavior. It can also lead to increased impulsiveness and aggression. Damage to the temporal region of the cerebral cortex often leads to impairment in memory and use of language.

This may be one reason that alcohol abuse is so difficult to treat: it damages the specific neural systems that are needed for drinkers to abstain from or curb their drinking.

The researchers note that their findings aren't all doom and gloom for people with an alcohol problem. Some of the damaged brain tissue is repaired once people stop drinking. So problem drinkers do have a lot to gain from changing their behavior.

An article on the study was published online by Alcoholism: Clinical and Experimental Research on September 15, 2011 and will also appear in the December print issue of the journal.