WASHINGTON — Psychiatrists are significantly less likely than doctors in other specialties to accept insurance, researchers say in a new study, complicating the push to increase access to mental health care.

The study, published Wednesday in the journal JAMA Psychiatry, found that 55 percent of psychiatrists accepted private insurance, compared with 89 percent of other doctors.

Likewise, the study said, 55 percent of psychiatrists accept patients covered by Medicare, against 86 percent of other doctors. And 43 percent of psychiatrists accept Medicaid, which provides coverage for low-income people, while 73 percent of other doctors do.

The lead author of the study, Dr. Tara F. Bishop of Weill Cornell Medical College in New York, said: “In the wake of the school killings in Newtown, Conn., and other recent mass shootings, the need for increased mental health services is now recognized. But unless patients have deep pockets, they may have a hard time finding a psychiatrist who will treat them.”