Decoded: How people turn alcoholics

London: Researchers have identified changes in the brain that may make people prone to excessive drinking, an advance that can lead to the development of new drug therapies to treat alcoholism.

The brain tissue of persons with alcohol dependence shows a variety of changes compared to non-alcoholic control persons, according to researchers from University of Eastern Finland.

All alcoholics' brains share some characteristics, but some are exclusive to the brain tissue of anxiety-prone type 1 alcoholics or impulsive type 2 alcoholics, they said.

Researchers analysed post-mortem brain tissue from alcoholic persons and non-alcoholic controls. Alcoholics were divided into two groups - type 1 and type 2 alcoholics.

Type 1 alcoholics develop alcohol dependence relatively late in life, and they are prone to anxiety, researchers said.

Type 2 alcoholics develop alcohol dependence at a young age and they are characterised by antisocial behaviour and impulsiveness, they said.

"From the viewpoint of the study setting, this division was made in order to highlight the wide spectrum of people suffering from alcohol dependence," said Olli Karkkainen from University of Eastern Finland.

"The reality, of course, is far more diverse, and not every alcoholic fits into one of these categories," said Karkkainen.

One of the changes shared by all alcoholics were increased levels of dehydroepiandrosterone in the brain.

Dehydroepiandrosterone is a steroid hormone that affects the central nervous system, researchers said.

These increased levels can, for their part, explain alcohol tolerance, which develops as a result of long-term use and in which alcohol no longer causes a similar feeling of pleasure as before, they said.

Moreover, all alcoholics showed decreased levels of serotonin transporters in posterior insula and posterior cingulate cortex, brain regions associated with recognition of feelings and social cognitive processes, researchers said.

This finding could be related to social anxiety type behaviour seen in alcohol dependent individuals, they said.

"These findings enhance our understanding of changes in the brain that make people prone to alcoholism and that are caused by long-term use," said Karkkainen.

"Such information is useful for developing new drug therapies for alcoholism, and for targeting existing treatments at patients who will benefit the most," he said.

The findings were published in the journals Alcohol and Alcoholism, Psychiatry Research: Neuroimaging, and Alcohol.