KUOPIO, Finland, April 29 (UPI) -- Although there are similarities between the brains of alcoholics, researchers in Finland report they have found differences that separate most into two groups depending on their basis for drinking.
Most drinkers qualify as either anxiety-prone type 1 or impulsive type 2, differences based on individual personalities and the effects of which damage receptors in different parts of the brain.
In terms of personality, type 1 alcoholics tend to be prone to anxiety and develop dependence later in life, while type 2 alcoholics develop a dependence at a young age and typically exhibit antisocial behavior and impulsiveness, according to researchers.
Between 10 and 15 percent of the Western population is dependent on alcohol, thought to cause a greater burden to society than all other illicit drugs combined. Understanding the differences between alcoholic individuals may lead to better treatments for the condition, researchers say.
"These findings enhance our understanding of changes in the brain that make people prone to alcoholism and that are caused by long-term use," Olli Kärkkäinen, a doctoral student at the University of Eastern Finland, said in a press release. "Such information is useful for developing new drug therapies for alcoholism, and for targeting existing treatments at patients who will benefit the most."
For the study, published in the journal Alcohol, researchers examined brain samples from 14 alcoholic individuals and 10 non-alcoholic individuals, finding some similarities, but that parts of the brain affected by alcohol differ based on the person's type of dependence.
All people who were dependent on alcohol were found to have increased levels of dehydroepiandrosterone, a hormone that is credited with alcohol tolerance among people who drink. All dependent participants also showed lower levels of serotonin transporters in the posterior insula and posterior cingulate cortex -- parts of the brain related to social anxiety, often seen in people with alcohol addiction.
In type 1 alcoholics, changes were seen to the endocannibinoid system, which modulates stress responses, while type 2 alcoholics were found to have increased levels of AMPA receptors in the anterior cingulate cortex, which play a role in behavioral learning and regulation.
Although researchers note not all people with alcohol dependence fit neatly into one of these groups, better understanding of the chemistry of dependence may help treating these people, they said.