Suicide attempts in the United States showed a “substantial and alarming increase” over the last decade, but one number remained the same, a new study has found: Year in and year out, about 40 percent of people who had recently tried suicide said they were not receiving mental health services.

Among the major findings was that there was no significant change in the use of mental health services by people who had tried suicide, despite the passage of the Affordable Care Act in 2010 and receding stigma around mental health care.

Over the 11-year period, a steady rate of about 40 percent of people who tried suicide in the previous year said they were not receiving mental health care, said Greg Rhee, an assistant professor of psychiatry at the Yale School of Medicine and one of the authors of the study.

The Affordable Care Act, which took effect fully in 2014, required all health plans to cover mental health and substance abuse services, and also sharply reduced the number of uninsured people in the U.S.

Still, many respondents to the survey in the new report said the cost of mental health care was prohibitive; others said they were uncertain where to go for treatment or had no transportation.

Since people who try suicide have a higher likelihood of making another attempt in the next six months compared with the general population, the barriers to treatment are particularly troubling, he said.

population as a whole is using mental health services at a higher level than ever before, with recent research suggesting that one in four Americans was receiving some care, Dr.

The population of people who have tried suicide is distinct, demographically, from those who have died by suicide: While women make up a majority of suicide attempts, more than three-quarters of those who die by suicide are men, the data shows, among other reasons because men are more likely to use guns.

Nestadt, who was not involved in the study, said the new data points, once again, to the scarcity of psychiatric beds or mental health professionals who take insurance, factors that have prevented medical science from bringing down the country’s suicide rates