A gene that affects the brain's dopamine system appears to have influenced mothers' behavior during a recent economic downturn, researchers say.
At the beginning of the recession that began in 2007, mothers with the "sensitive" version of a gene called DRD2 became more likely to strike or scream at their children, the researchers say. Mothers with the other "insensitive" version of the gene didn't change their behavior.
But once it appeared that the recession would not become a full-fledged depression, the "sensitive" mothers became less likely than "insensitive" mothers to engage in harsh parenting.
"You have the same genes, and with a different environment it's a completely different story," says Irwin Garfinkel, a professor of contemporary urban problems at Columbia University. "I think that's the most amazing part of what we found."
Garfinkel and four other researchers published the results in the Proceedings of the National Academy of Sciences.
The surprising finding came about because Garfinkel and the other researchers happened to be studying "fragile" families in 20 large cities when the 2007 recession began. One of the things they were tracking was reports of harsh parenting, including spanking, hitting or screaming at a child, he says.
Previous research had found that harsh parenting is more common during economic hard times, so Garfinkel says that's what researchers expected to see during the 2007-2009 period, often called the Great Recession.
The team was puzzled by the reports that harsh parenting, despite rising initially, actually declined as the recession got worse. Dohoon Lee, an assistant professor of sociology at New York University, suggested that the mothers' genes might offer an explanation.
The team focused on the DRD2 gene because the dopamine system affects how people feel, and that particular gene is known to be associated with aggressive behavior. They looked at genes only from mothers because it would have been more expensive and more difficult to include fathers.
The results suggest that mothers with the "sensitive" gene were reacting not to the economic downturn itself, but to the fear that things would get really bad, Garfinkel says. Once it began to look as if a complete economic collapse wasn't going to happen, he says, they seemed to relax and became less harsh than the moms with the "insensitive" dopamine gene.
That explanation fits nicely with a theory of genetics that is often explained in terms of orchids and dandelions.
Dandelions tend to do pretty well regardless of whether conditions are good or bad. Orchids, on the other hand, die in poor conditions, but in the right environment, they thrive and become "one of the most beautiful plants on the planet," Garfinkel says.
Moms with the sensitive dopamine gene appear to behave like orchids, Garfinkel says, parenting badly when things look bleak, but really well when things are better than they expected.
That conclusion is consistent with a new understanding of the brain's dopamine system, says Michael Frank, a neuroscientist at Brown University. Scientists used to think brain cells in this system responded to rewards — like good news. But that's changed, Frank says.
"It's now known that they don't react to rewards per se," he says. "[Brain cells] increase their level of activity when the outcomes are better than expected and they decrease when the outcomes are worse than expected."
So if you were expecting the next Great Depression, your dopamine system would make you feel better when it didn't occur.
But genetic studies like this one are tricky and need to be replicated, Frank says. One possibility is that the mothers' behavior was correlated not only with changes in the dopamine gene but with other genes that might be even more important.
AUDIE CORNISH, HOST:
From NPR News, this is ALL THINGS CONSIDERED. I'm Audie Cornish.
MELISSA BLOCK, HOST:
And I'm Melissa Block. Hard economic times can change people's behavior, including how they parent. Now, researchers think they've found a reason why adversity changes some mothers more than others. NPR's Jon Hamilton reports on the discovery of a gene that's associated with harsh parenting.
JON HAMILTON, BYLINE: In late 2007, the U.S. was just entering a major economic downturn. At the same time, a team of researchers happened to be studying vulnerable families in 20 large American cities. Irv Garfinkel, of Columbia University's School of Social Work, says one of the things they were measuring was harsh parenting.
IRWIN GARFINKEL: Spanking, hitting, that sort of thing; also includes screaming at the child.
HAMILTON: Previous research had found that harsh parenting is more common during economic hard times, so Garfinkel says that's what they expected to see during the period often called the great recession. And in the early months of rising unemployment, he says, they did.
GARFINKEL: But as unemployment continues to increase, harsh parenting actually declines.
HAMILTON: That was surprising and confusing. At least it was until a researcher at New York University named Dohoon Lee suggested looking for a genetic explanation. The team focused on a gene called DRD2. It's part of the brain's dopamine system, which influences how we feel. They were only able to study this gene in mothers. Garfinkel says there are two versions of the dopamine gene, one known as sensitive, the other as insensitive. And how moms parented at the beginning of the recession was associated with which version of the gene they carried.
GARFINKEL: If you have the sensitive version of the gene, then you're more likely to harsh parent. If you have the insensitive version of this gene, you're not affected at all by the recession.
HAMILTON: Garfinkel says it appears that mothers with the sensitive gene were reacting to the fear that things would get really bad. And as it began to look like we weren't headed for a depression, they relaxed and began to exhibit less harsh parenting than the moms who didn't react to the recession.
GARFINKEL: You have the same genes, and with a different environment, it's a completely different story. I think that's the most amazing part of what we found.
HAMILTON: And it fits in nicely with a theory of genetics that is often explained in terms of orchids and dandelions. Garfinkel says dandelions tend to do pretty well even in really bad conditions. Orchids, not so much.
GARFINKEL: The orchid, we know, in poor conditions wilts and dies. In really good condition, the orchid is one of the most beautiful plants on the planet.
HAMILTON: Orchids are sensitive, but they do better than dandelions under the right conditions. And you could say the same thing about moms with the sensitive dopamine gene. Michael Frank at Brown University says the finding is consistent with a new understanding of the brain's dopamine system. He says scientists used to think brain cells in this system responded to rewards, like good news.
MICHAEL FRANK: It's now known that they don't react to rewards per se. It's that they increase their firing or the level of activity when the outcomes are better than expected, and they decrease when the outcomes are worse than expected. So it's precisely in those kind of situations where your expectations set the way the dopamine system is going to respond.
HAMILTON: If you were expecting the next Great Depression, your dopamine system would make you feel better when it didn't occur. But Frank says genetic studies like this one are tricky. For example, he says it's not clear whether the mother's behavior was correlated only with variations in the dopamine gene.
FRANK: It also could be correlated with a host of other genes that are associated with other things that we don't know.
HAMILTON: Like serotonin, another gene involved in how we feel. The new research appears in the Proceedings of the National Academy of Sciences. Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.