Access to mental health providers and medication has dropped, a new study says, although federal lawmakers have enacted legislation in recent years to bolster private and public coverage of mental health treatment.

The findings were assembled by researchers from New York University's Langone Medical Center, who published details of their report online Monday in the journal Psychiatric Services. Using data from the Centers for Disease Control and Prevention, they found that the incidence of people who report having a form of serious psychological distress, such as anxiety or depression, has increased to about 3.4 percent of the U.S. population, which comes to 8.3 million adults. Previous estimates had pinned the number closer to 3 percent.

That increase occurred even as the federal government made efforts to boost access to mental healthcare, first through the passage of the 2008 Mental Health Parity and Addiction Equity Act, which allowed behavioral health specialists to be reimbursed at the same level as physical health specialists, and then through Obamacare in 2010, which required all health insurance plans to provide coverage for treating mental health conditions.

Last year, former President Barack Obama also signed the 21st Century Cures bill into law, which encourages states to use mental health block grants to provide early intervention for psychosis.

As the incidence of mental health conditions increased, however, access decreased, according to the study. In 2014, the year that people began receiving coverage through Medicaid expansion in some states or through government-subsidized private plans, 9.5 percent of U.S. adults who were in distress reported that they didn't have health insurance that would give them access to a psychiatrist or counselor, compared with 9 percent in 2006. About 10.5 percent had delays seeing professionals in 2014, compared with 8.7 percent in 2006.

Paying for prescriptions also appeared to become a greater challenge. In 2014, 9.9 percent reported they could not pay for their medications, up from 8.7 percent in 2006.

"Although our analysis does not give concrete reasons why mental health services are diminishing, it could be from shortages in professional help, increased costs of care not covered by insurance, the great recession, and other reasons worthy of further investigation," said Judith Weissman, an epidemiologist at NYU Langone and the study's lead investigator.

She added that her report could serve as a baseline for evaluating the impact of the laws in future years.

It's not clear what direction treatment access would take under proposals from Republicans to repeal portions of Obamacare. Through the repeal bill, the American Health Care Act, GOP lawmakers have floated the possibility of undoing the 10 essential health benefits that every health plan is required to provide, which includes coverage for mental health, though they have added $15 billion to a stability fund specifically to help address mental health.