WASHINGTON — If you're uninsured, getting on Medicaid clearly improves your mental health, but it doesn't seem to make much difference in physical conditions such as high blood pressure.

The counterintuitive findings by researchers at Harvard and MIT, from an experiment involving low-income, able-bodied Oregonians, appear in Thursday's New England Journal of Medicine. The study offers a twist for states weighing a major Medicaid expansion under President Barack Obama's health care law, to serve a similar population of adults around the country.

"The study did not generate any evidence that Medicaid coverage translated to measurable improvements in physical health outcomes over a two-year window," said lead researcher Katherine Baicker of the Harvard School of Public Health. "It did generate robust improvements in mental health and enormous reductions in financial strain and hardship."