Nearly 17 million American adults had an alcohol-use disorder in 2013, and about 1.3 million received treatment, according to the National Institute on Alcohol Abuse and Alcoholism.
But not everyone who drinks develops an alcohol-use disorder. Not even close.
In 2013, about 87 percent of adults reported they had drank alcohol at some point in their lives; 56 percent said they drank in the previous month.
So why are some people at risk for developing alcoholism while others can safely consume alcohol and enjoy its health benefits?
That’s something Kathleen Grant has devoted decades to understanding. Grant is a senior scientist and head of the division of neuroscience at the Oregon National Primate Research Center at Oregon Health & Science University.
She hopes her research will lead to an understanding of who is at risk for developing alcoholism and how to detect those at risk before they’ve developed an addiction.
“Treatment is really important, but prevention would be so much better for everyone because alcoholism affects more than just the individual,” Grant said.
Grant’s research seeks to provide a better understanding of the known risk factors for alcohol abuse and the consequences of heavy alcohol consumption. A person’s family history of alcoholism, the age at which they started drinking regularly (particularly to intoxication), their gender, stress levels, availability of alcohol and genetics are all known risk factors, Grant said.
Grant’s research isolates those variables. That’s difficult to do in humans, who would be relied upon to self-report, she said. That’s why researchers turn to animals. With animals, researchers know exactly how much alcohol is being consumed and can control their history, nutritional status and other factors, Grant said.
“One thing we’ve found in the studies is some animals find alcohol intoxication aversive, whereas others drink in a manner that ensures they’ll get intoxicated,” Grant said.
Animals that find intoxication aversive sip their drinks. The animals that are chronically self-intoxicating will gulp their drinks, Grant said. Researchers can assume that the animals that regularly down their drinks quickly are drinking to get intoxicated, while the other animals might be drinking because something else about the alcohol is attractive, such as its source of calories or ability to increase sociability, Grant said.
The reasons why some animals and, in turn, some people, are driven to patterns of heavy drinking while others can drink in moderation vary, Grant said.
For some, the intoxicating effects of alcohol are not pleasant, so they avoid it. For others, intoxication might be enjoyable, so they repeat the behavior, Grant said. When people continue to repeat intoxication behavior, that’s when it can become problematic, she said.
“If your organs, like your brain, are working and being exposed to these high concentrations, you have a chance of modifying the genes that are being expressed,” Grant said.
The brain is full of activity. There’s chemical messaging and electrical messaging. There’s activity occurring that helps a person sit or stand or keeps their heart beating.
If the cells performing those functions are being exposed to high concentrations of alcohol, there’s a chance the genes that were turned on to perform those functions can be modified by the presence of the alcohol, Grant said. The modification might happen in some cells and not others, depending on how active they are in the brain and the level of exposure, she said.
But when the person becomes sober again, those gene modifications remain. That means the genes will do what they’re programmed to do, but some might be programed to respond to alcohol and, as a result, might need alcohol there to function, Grant said.
“That could be a cellular basis of dependence,” she said.
Reversing those changes is possible, but it requires a long, sustained period of time without alcohol, Grant said.
Grant said she hopes her research will be able to identify whether there are general genes that get modified that would be common to all cells or just to specific cells.
“If we can find something that’s common in blood and in brain — the same amount of alcohol modifies the same genes to the same extent — then we have a biomarker of what’s going on in the brain,” Grant said. “You could have a panel of biomarkers that would tell you you’re starting to modify your genes in a way that would be consistent with risk for heavy drinking.”
Such tests could be performed in doctors’ offices and could be used to warn people before they reach the point of alcohol abuse, essentially cautioning people that they’re heading toward addiction.
“That would be pretty cool,” Grant said.
