The more residents with serious mental illness, the more likely a nursing home is to have fewer direct-care staffing hours and other substantial differences from its peers, a new study finds.

Nursing homes increasingly are serving more residents with serious mental illness, with a large number of these adults concentrated in a few facilities, according to researchers from the University of South Florida and Miami University, Ohio. These operators report more Medicaid-paying residents, and lower scores on all Nursing Home Compare star ratings in comparison to all other nursing homes. They are also more likely to be for-profit operations, wrote first author Dylan J. Jester.

“These [operations] are uniquely different from typical nursing homes in terms of facility characteristics, staffing, and care practices,” he wrote. Nursing home providers and public policy makers should be aware of this population’s “unique — and potentially unmet — needs,” he concluded.

Full findings were published in the journal Gerontologist.