Though Connecticut has one of the most robust child mental health care systems in the nation, many of the state’s services are underused, according to a study published last month by the Child Health and Development Institute.

The report, which focuses on school-based care as a model of increasing access to children across Connecticut, finds that the availability and use of mental health services vary vastly between school districts. In districts that fail to meet students’ mental health issues, the report notes, students are more likely to perform poorly in class, exhibit disruptive behavior and end up in the juvenile justice system.

In the past decade, educators and mental health providers have noted an anecdotal but pronounced rise in the prevalence and intensity of mental health issues in young children, according to Jesse White-Frese, executive director of the Connecticut Association of School-Based Health Centers.

Based on national statistics, the report’s authors estimate that 160,000 children in Connecticut — one in five — exhibit mental health issues, and about 20 percent receive the level of care they require. If these projections are accurate, nearly 125,000 children do not receive adequate care.

“One of the challenges is that things in Connecticut happen in isolation,” said Jeana Bracey, senior associate at the Child Health and Development Institute. “There are a lot of really great services, but they’re all happening in a vacuum.”

The report cites a program known as the School-Based Diversion Initiative, or SBDI, as a model for linking the array of available child services across a community under the schoolhouse roof. Though the initiative has a targeted goal of reducing the number of arrests in schools, the hub of children’s mental health services it creates has considerably increased the use of available mental health services in the districts where it is run, Bracey said.

“The report highlights the need and the opportunity for schools to be the center for delivering mental health care by virtue of the fact that it’s where kids spend a majority of their time,” said Sara Frankel, public policy director for children and young adults at the National Alliance of Mental Illness Connecticut. “It doesn’t mean [the services] have to be through school personnel.”

The Child Health and Development Institute manages SBDI programs in nine school districts across the state, but its small staff is not equipped to run more programs, Bracey said.

In addition, the state opened 13 school-based health care clinics that offer students medical and psychological services regardless of their ability to pay. But due to lack of funding, the state did not open any additional clinics until this fall, when four new clinics — a line item in Gov. Dannel Malloy’s 2012 education reform package — opened their doors.

Still, the report notes, some districts lack even basic mental health personnel. About 15 percent of the state’s school districts do not employ a social worker, according to the report.

Many of the state’s teachers have not been trained in mental health first aid, so they often resort to suspension, expulsion or arrest when faced with a behavioral crisis, the report notes. Under the mental health legislation that arose in May from the shooting at Sandy Hook, all educators will now be required to be trained in mental health first aid.

The disparity can be seen in the differing use of Emergency Mobile Psychiatric Services, or EMPS, a psychiatric crisis hotline free for all children in Connecticut. Though schools are the second-most frequent users of this service after families, some schools use it only sparingly, and some do not use it at all.

“There’s this conception that the service is just for students who say, ‘I want to hurt myself right now,’” Bracey said.

One of the largest barriers to access, according to the report, is the lack of a connecting structure run at the statewide level to link different state-funded mental health services to one another. Many school districts lack adequate mental health staff, but do not connect students to community-based providers.

When a student is treated by EMPS, mental health providers at his or her school are not informed.

“We’re ahead of other states in the services we offer,” Bracey said. “And so having a statewide oversight of that, a statewide framework, will help make that a smoother system overall.”

In a 2009 report, the National Alliance on Mental Illness rated Connecticut’s mental health system as a B, higher than the national average of a D.