U.S. healthcare providers need to prepare for a big increase in the number of elderly people with dementia and other mental illnesses, according to a new study.

Researchers at Queen’s Medical Center in Honolulu found that a number of factors contribute to the uptick in seniors with mental illnesses. One is growth: It’s expected that 20% of the U.S. population will be 65 or older by 2030. Americans also are living longer with dementia and psychiatric illnesses that can lead to problematic behavior, such as aggression, delusions and wandering, the investigators said in a presentation at an American Psychiatric Association meeting this week.

The researchers studied emergency room records and noticed an overall increase in visits by elderly people with mental illnesses in recent years. They saw a 30% jump between 2008 and 2009 alone. These patients were often brought to the ER by exhausted family caregivers or nursing home workers who weren’t equipped to handle violence and other severe symptoms. Investigators also observed an increase in 911 calls from desperate caregivers.

All in all, elderly people with mental illnesses have become an underserved segment of the population, the researchers said. Experts say more geriatric psychiatrists will be needed in the future to handle these problems.

“We need to have the resources to help this population and help the caregivers of this population who are stuck in the middle,” said Dr. Jeffrey Borenstein, M.D., chairman of Council of Communications for the APA, told the Los Angeles Times.