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And I'm David Greene. In a few weeks, the Supreme Court is expected to weigh in on the constitutionality of same-sex marriage. We have heard a lot about the debate. This morning, something different. We're taking a look at whether gay marriage laws have health consequences. NPR's Shankar Vedantam, who regularly joins us to talk about interesting social science research, is in the studio with us. Shankar, welcome back.
SHANKAR VEDANTAM, BYLINE: Hi, David.
GREENE: OK, Shankar. When we talk about bans on same-sex marriage, some talk about it as a matter of prejudice, some talk about it as a matter of tradition in their minds. You're focusing on something different here.
VEDANTAM: That's right, David.
I found some really interesting research that looks at what the mental health consequences are of same-sex marriage bans in the many states that have passed these bans.
GREENE: And we have something like three dozen states with bans in place, right?
VEDANTAM: That's exactly right. And many of these bans were actually enacted around 2004. And it turns out the timing of those bans have given us a natural experiment. Right before 2004, the National Institutes of Health conducted this massive of 30,000 Americans tracking mental health disorders across the country. And then they went after 2004 and spoke to the very same people over again.
I interviewed Mark Hatzenbuehler. He's a researcher at Columbia University. He tracked mental disorders among gays and lesbians before and after states passed these bans on same-sex marriage. And he told me that gay people in states that ban same-sex marriage suffered a significant increase in psychiatric disorders.
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GREENE: Two-hundred-forty-eight percent increase in anxiety disorders after bans? That sounds enormous.
VEDANTAM: To put it in perspective, David, he's saying the number of gays and lesbians in these states who had generalized anxiety disorders more than doubled. I mean, so the specific numbers are they went from 2.7 percent to 9.4 percent.
GREENE: After bans took effect.
GREENE: But we should hang on a second. I mean, do we know that these changes were directly related to these laws? Or there could've been a lot of other things going on.
VEDANTAM: Yeah, good question. I asked Hatzenbuehler that and he told me that he tracked the mental health of gays and lesbians who lived in states that didn't pass these bans and he also tracked the mental health of heterosexuals in stated that did pass the bans. And he found these other groups did not see similar increases in mental health problems.
The increase in psychiatric disorders was experienced only by gays and lesbians and only in states that passed the bans.
GREENE: This is what scientists call controlling. I mean...
GREENE: ...nailing it down to one cause of something.
GREENE: OK. On the flip side, Shankar, do we have evidence from states that have approved same-sex marriage?
VEDANTAM: Yes. So Hatzanbuehler conducted one study looking at 1,200 gay men in Massachusetts at a community health center. And he found that after Massachusetts passed a law approving gay marriage, the number of visits to doctors and costs for health care went down. And he found that there was a reduction in disorders that were linked to stress. So disorders like hypertension or depression or adjustment disorders.
GREENE: So it sounds like we're talking about stress, the common denominator. In states that approve same-sex marriage, there's less stress. In states that have banned same-sex marriage, there's more stress among gays and lesbians.
VEDANTAM: Yes. And I think that's exactly what Hatzenbuehler says, and it's also what gays and lesbians in many states that pass these bans are reporting.
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