William Johnston, a representative from Columbus House, said 100 to 150 people stay in the New Haven shelter each night. Eight or nine are usually turned away.

Johnston calls the plight of the homeless a “downward spiral,” because mental illness, substance abuse and a lack of affordable housing can add to the initial problem of homelessness. But a recent Yale Medical School study showed that a combination of housing vouchers and intensive case management at just a slightly increased cost can help alleviate more effectively the problems of mentally ill homeless people.

According to the National Advisory Mental Health Council, 35 percent of homeless people have severe mental illness.

The medical school conducted the study in association with the Veterans’ Association and randomly selected 460 mentally ill homeless veterans from Cleveland, San Francisco, New Orleans and San Diego to participate in the research. The study divided the veterans into three groups and tracked them over a three-year period, epidemiology and public health professor Robert Rosenheck said in a press release.

One group received only the standard VA treatment, which includes mental and physical healthcare, but no additional housing provisions. A second group also received case management, and the third group received housing vouchers in addition to the other benefits.

Rosenheck said case managers would meet individually with each veteran in a comforting, community environment to help the client work through the complex service system. Case managers would also provide support and encouragement to the veterans.

In addition to case management, the veterans in the third group received housing vouchers to be used toward independent apartments. The vouchers were for the government-determined fair market rent, minus 30 percent of the veterans’ income.

The results of the study implied that, with the combination of housing vouchers and case management, veterans were housed 25 percent more often than those receiving standard VA treatment, which includes mental and physical healthcare. The group receiving only case management was housed only 7 percent more days than the standard VA group. These findings translate into the possibility for decreased time on the streets for the mentally ill, whose fragile condition is often exacerbated by the challenges of homelessness.

Yet, according to the study, this comes at a price.

“If we make vouchers available, we can reduce homelessness, but it costs money,” Rosenberg said in an e-mail. “We would need to make a national commitment to spend more for homeless people.”

Johnston agreed. He said homelessness is not just a problem for those unlucky few who suffer its difficulties; it is everyone’s problem.

When people are homeless, Johnston said their self-esteem diminishes, making them more susceptible to substance abuse and less likely to find employment. Unemployment and substance abuse are the pivotal problems for the homeless, he said.

“We continue to victimize the victim,” Johnston said. “Some people have no other way of taking care of themselves.”