For years, overwhelming anecdotal evidence that alcoholism is genetic has led many parents to hope that their children’s relationship with drinking will be different than their own or their spouse’s.
In recent years, however, science has begun to show us – overwhelmingly, in fact – that if your parent has a drinking problem, there’s a good chance you may develop a problem with alcohol, too. But is it due to genetics, environment or a bit of both?
Researchers at Purdue and Indiana universities recently completed the latest experiment aimed at sorting this all out. Their work, published in PLoS Genetics, took decades to complete.
While “nurture” is a big part of what makes an alcoholic, “nature” is too. Preventing a child with genes that are vulnerable to addiction from becoming an alcoholic can be a challenge even for sober parents who don’t keep liquor in the house. Likewise, when somebody becomes an alcoholic, blaming it entirely on their parents’ genetics doesn’t provide the answers, researchers say.
Genome Sequencing Reveals 930 ‘Heavy Drinking’ Genes
In this latest research led by William Muir of Purdue University, he and colleague Feng Zhou from Indiana University began with a population of genetically diverse rats. Then, they bred two lines – “one group that displayed classic clinical signs of alcoholism and another that completely abstained from alcohol,” according to a Purdue news release.1
“Understanding the genetic basis (of alcoholism) is critical to comprehend, treat and prevent this disease, but difficult in humans, as choice is influenced by nature and nurture,” the authors wrote in the study summary.2 “To discover its genetic basis, we used an animal model system that controlled for genetic and non-genetic factors through sequencing in breeds that were either compulsive excessive drinkers or completely abstinent. We discovered consistent alterations in several genes and neurological pathways previously unassociated with alcoholism. These results strengthened our understanding of the genetic basis of alcoholism and revealed potential genetic and neurologic-based treatments.”
The researchers performed complete genome sequencing from 10 rats in each line. They found 930 genes associated with heavy drinking, “the vast majority of which are in genetic regulatory regions, not coding regions, as many researchers previously expected,” according to the news release. “Muir compared coding regions to a car and regulator regions to the gas and brake pedals that determine the car’s speed.”
“We all have the genes for alcoholism, but our genetic abilities to control it differ,” Muir said in the news release.
“We all have the genes for alcoholism, but our genetic abilities to control it differ.”
Rats with Heavy Drinking Genes ‘Preferred Alcohol to Water’
Why did it take several decades to breed rats that were hardcore drinkers? Like most humans, rats tend to know when enough is enough. But enough breeding and re-breeding of the rats “yielded a line of rats that compulsively drank to excess, preferred alcohol to water, drank to maintain intoxication, performed tasks to receive alcohol and showed signs of withdrawal if alcohol was not present,” according to the news release.
“Under the influence of alcohol, some rats became docile and fell asleep in a corner while others became aggressive,” Zhou said in the news release.
In other words, some behaved differently from others, just like humans with drinking problems.
“It’s not one gene, one problem,” Muir said in the news release. “This trait is controlled by vast numbers of genes and networks. This probably dashes water on the idea of treating alcoholism with a single pill.”
In fact, previous research on mice already has shown that alcoholism is controlled by gene networks. Reporting on a study in Molecular Psychiatry in 2014 by researchers at the University of Texas at Austin, Healthline News reported, “certain genes cluster together inside the brain, much like drinking buddies of all types gather around the bar. It’s an important discovery, because it goes beyond simply identifying genes known to exist among drinkers to show how they conspire to create disease and dependence.”3
Recovery Is Possible Regardless of Your Bloodline
The Indiana researchers did identify one region in particular – the glutamate receptor signaling pathway – as a possible treatment target because of the large number of alcoholism genes it contains, according to the news release. Next, researchers will need to confirm whether the genes found in alcohol rats also control alcoholism in humans.
Meanwhile, help is available for alcoholics, even those from families with strong bloodlines of heavy drinking.
Brandon T. had his first drink of alcohol “around the age of 14 and later added opiates to the substances he used,” according to his story published on Heroes in Recovery, a website that celebrates sober living.4 “There is a long history of addiction and alcoholism on one side of his family, and he believes this may have given him a genetic predisposition. Fortunately, most of his family is in recovery as well.”
According to Brandon, “don’t give up before the miracle happens.”
Brandon, who now works in a halfway house, plans to finish his degree, live a stable life in recovery and go back to his small-town home. “He calls himself a farm boy, and his family has had a large cattle operation for several generations,” according to his Heroes in Recovery profile. “He has a very good relationship with his family again, although restoring this relationship did not happen overnight.”
1. van Hoose, N. (2016, Aug. 4). Drink-seeking rats provide sobering look into genetics of alcoholism. Purdue University Agriculture News. Retrieved Oct. 3, 2016, from https://www.purdue.edu/newsroom/releases/2016/Q3/drink-seeking-rats-provide-sobering-look-into-genetics-of-alcoholism.html
2. Chiao-Ling, L. et al. (2016, Aug. 4). High Resolution Genomic Scans Reveal Genetic Architecture Controlling Alcohol Preference in Bidirectionally Selected Rat Model. PLOS Genetics. Retrieved Oct. 3, 2016, from http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1006178
3. Heitz, D. (2014, Dec. 9). Scientists find first gene network linked to alcoholism. Healthline News. Retrieved Oct. 3, 2016, from http://www.healthline.com/health-news/scientists-find-gene-network-linked-to-alcoholism-120914
4. Johnson, S. (2015, Dec. 9). Brandon T.: Don’t give up before the miracle happens. Heroes in Recovery. Retrieved Oct. 3, 2016, from http://heroesinrecovery.com/stories/dont-give-up-before-the-miracle-happens/
Written by David Heitz