Elderly nursing home residents are increasingly living alongside young and middle-age people with mental illness, with sometimes tragic results, according to a 50-state investigation by the Associated Press. It appears that in many cases this potentially dangerous trend is a violation of federal law.

According to the AP, nearly 125,000 non-elderly adults with serious mental illness were living in U.S. nursing homes in 2008. This is a 41 percent increase from 2002. Younger mentally ill people now account for more than 9 percent of the nation’s nearly 1.4 million nursing home residents.

The AP concluded that nursing homes have become “dumping grounds” for the mentally ill. This seems to be happening for a combination of reasons: state mental institutions are closing, there is a shortage of hospital psychiatric beds, and nursing homes have more room because today’s elderly are healthier and states are increasingly encouraging potential nursing home residents to continue living in the community. Also, it can be advantageous for states to place mentally ill people in nursing homes because of quirks in how the federal government pays for mental health services.

Although no government agency tracks violence by mentally ill residents against elderly residents, the AP article cites a number of recent cases, including one in which a 77-year-old Alzheimer’s patient died when his roommate, a mentally ill man 30 years his junior, allegedly smashed him in the face with a clock radio.

A 1987 federal law says that patients suffering from mental illness other than dementia cannot be admitted to Medicaid-certified nursing homes unless they need the high level of care a nursing home can provide. But this clearly hasn’t slowed the influx of the mentally ill into nursing homes.