As people age and their mental capacities decline, they can often be targeted by scammers seeking easy cash.

But more often than not, this "financial abuse" comes not from a stranger, but from a trusted family member, research from the University of Southern California (USC) shows.

"Despite the high rates of financial exploitation perpetrated by scammers targeting older adults, we found that family members were the most commonly alleged perpetrators of financial abuse," said lead study author Gail Weissberger. "In fact, across all abuse types, with the exception of sexual abuse and self-neglect, abuse by a family member was the most commonly reported."

Weissberger is a postdoctoral scholar at USC's School of Medicine. Her team analyzed nearly 2,000 calls to the National Center on Elder Abuse (NCEA) resource line, created to help people seeking information on how to spot or report elder abuse.

More than 41% of the calls reported alleged some form of abuse was taking place, and of those cases, nearly 55% involved financial abuse.

Of all the abuse-related calls, family members were the alleged perpetrators in nearly 48% of calls in which the researchers could determine a relationship.

Financial abuse was the most common type of abuse by family members (nearly 62%), followed by emotional abuse (35%), neglect (20.1%), physical abuse (12%) and sexual abuse (0.3%).

Of calls alleging abuse by a family member, more than 32% involved more than one type of abuse, the study found.

One in 10 U.S. seniors experience some type of abuse each year, but the problem often goes unreported, the USC team noted. Besides its physical, mental, social and financial impacts on seniors and their families, elder abuse results in more than $5.3 billion in health care costs each year in the United States.

The new findings "highlight the importance of developing effective strategies to prevent future abuse," Weissberger said in a USC news release. "Our next step is to conduct more studies targeting high-risk individuals and to better understand additional risk factors."

In the meantime, seniors and those concerned about their welfare need resources to turn to, said study co-author Duke Han, an associate professor of family medicine at USC.

The NCEA resource line "serves as a public access point for people seeking information and resources about elder abuse," he said. "Our findings highlight the importance of resource lines for those seeking information on elder abuse, as many calls were made to understand whether certain situations reflected abuse."