At the outset, these women had very rough lives. Before HAART, 29 percent experienced domestic violence, while 28 percent used stimulants like crack cocaine. After the introduction of HAART, though, the rate of domestic violence among the women decreased by 10 percent, and the rate of drug use went down by 15 percent.

Surprisingly, the authors found changes to the women’s physical or mental health couldn’t explain the difference. Instead, there’s some evidence that their employment prospects improved. The relationship is speculative, but the authors suspect the women might have been motivated to give up drugs or get jobs because they knew they would be living longer. Once employed, the financial freedom might have allowed them to leave their abusive partners.

Right after the introduction of HAART, the researchers saw “hopefulness” increase among the HIV positive women—even though not all of the women were actually taking the treatment. The mere prospect of a healthy future, in other words, might have led them to make different decisions about their lives.

“If you give a group of people a longer lifespan, it gives them a chance to invest in themselves,” said lead author Nicholas Papageorge, a Johns Hopkins economist. “One element of that is the incentive to leave an abusive partner.”

The study didn’t capture what exactly the women were thinking, but it’s possible they could have ditched their violent partners once they realized they wouldn’t need someone to care for them as their AIDS progressed. Then, they might have thought, “we used to shoot up heroin together but now that he’s not around, I’m not going to do that anymore,” Papageorge suggested. “I bet you all of those things happened.”

The study is just another example, Papageorge said, of how access to health care doesn’t just extend lives, it can also affect seemingly intractable problems like violence or drug use. That finding echoes past work showing that advances in maternal health helped boost labor-force participation among women. The advent of prenatal care, antibiotics, and medicalized childbirth starting in the 1930s made it so women no longer lost 1.17 “life-years” to disabilities, such as rectovaginal fistulas, as a result of each pregnancy, that study found.

Though the AIDS crisis is now no longer at its peak, Papageorge said his study and others like it are a reminder that there can be surprising consequences to denying poor people access to health care. It’s something that’s worth keeping in mind as policymakers attempt, once again, to restructure the American health-care system in coming weeks.