The Great Recession of 2009 deepened income inequality - except for the government, a lot more people were out of work and scholars have correlated that to county-by-county rates of child maltreatment, from sexual, physical and emotional abuse to traumatic brain injuries and death.

The income inequality-child maltreatment correlation came using all 3,142 American counties from 2005-09, and the authors say it is one of the most comprehensive of its kind and the first to target child abuse in places with the greatest gap between rich and poor.  Nearly 3 million children younger than 18 are physically abused, sexually abused, physically neglected or emotionally abused each year in the United States, the authors noted. That is about 4 percent of the youth population. 

"Our study is the first to demonstrate that increases in income inequality are associated with increases in child maltreatment," said lead author John J. Eckenrode, Cornell University professor of human development and director of the Family Life Development Center in the College of Human Ecology. "More equal societies, states and communities have fewer health and social problems than less equal ones – that much was known. Our study extends the list of unfavorable child outcomes associated with income inequality to include child abuse and neglect."

"Certainly, poor counties with general, overall poverty have significant problems with child abuse. We were more interested in geographic areas with wide variations in income – think of counties encompassing affluent suburbs and impoverished inner cities, or think of rich/poor Brooklyn, New York – that's where income inequalities are most pronounced. That's where the kids are really hurting."

Abuse obviously has long-lasting effects.

"Child maltreatment is a toxic stressor in the lives of children that may result in childhood mortality and morbidities and have lifelong effects on leading causes of death in adults," the authors write. "This is in addition to long-term effects on mental health, substance use, risky sexual behavior and criminal behavior … increased rates of unemployment, poverty and Medicaid use in adulthood."