More mothers in prison.

More single mothers.

Undetected and untreated mental illness.

High divorce rates.

Susan Kelley is one of those experts. She’s the dean of the College of Health and Human Services at Georgia State University in Atlanta, and the founder/director of the National Center on Grandparents Raising Grandchildren.

“It’s incredible, the number of mothers - especially single mothers - incapacitated by substance abuse, incarceration and mental health issues,” said Kelley. “They’re a hidden population.”

The consequence, she said, is heavier reliance on grandparents to raise their children’s children, either voluntarily or through order of the courts. And frequently with little warning or preparation.

Kelley said social history holds that rearing children with blood relatives whenever possible is preferable to putting them up for random adoption or into the foster care system.

Yet this traditional preference, she added, places a not-so-hidden burden on grandparents who are not physically, financially or emotionally ready for the challenges of parenting in the age of the Internet, iPods and instant messaging.

Understanding how grandchildren view and respond to the world around them and how that differs from the time when the grandparents raised their first family requires a support system that’s often not there for them, said Kelley.

This can lead to social isolation characterized by frustration, resentment and even anger, she said.

Dorothy Carrillo, associate director for operations at Georgia State’s School of Social Work, said the changes go beyond grandma adjusting to high-tech gadgets and a high-speed lifestyle. She said common necessities can also overwhelm.

“One day your grandchildren don’t live with you, and the next they do,” said Carrillo. “We’ve had situations where there weren’t enough beds in the house or no crib, no diapers, no car seat.”

Add to the equation that many grandparents rely on little more than Social Security income and meager savings to get by, and the problem grows much larger, said Carrillo.

The American Association of Retired Persons estimates that about 20 percent of grandparent-headed households in the United States fall below the federal poverty guideline of $20,000 per year for a family of four.