New research suggests that children living in low-income households are more likely to have impaired cognitive abilities.

Researchers at the University of Rochester in New York found that children from impoverished families who have endured family instability and emotionally distant caregivers are at a greater risk for a "variety of developmental issues as they become older," Medical Daily reported.

"What we were interested in seeing is whether specific risk factors of children living in poverty might be related to children's cortisol levels," Jennifer Suor, lead author of the study, said in a statement. "Then we looked to see if the hormone levels are predictive of significant differences in the children's ability to think."

Based on their findings, researchers found that children in low-income, stressful home environments -- specifically homes with family instability and harsh and disengaged mothers -- can have adverse levels of cortisol in their bodies, which previously studies have associated with having damaging affects on the structure and function of children's brains.

Understanding how cortisol affects the brain's cognitive abilities, though, is still unclear.

"The exact mechanisms through which too much or too little cortisol affects cognitive functioning aren't fully understood," Melissa L. Sturge-Apple, coauthor of the study, said in a statement.

In the study, the children with family instability or harsh and emotionally distant caregivers at age 2, had elevated cortisol levels, while children with only family instability at age 2, had lower than average cortisol levels. Family instability includes frequent changes in care providers, household members, or residence

"We were surprised to find that the children's cortisol levels, which we test from a cheek swab, didn't change -- they remained relatively stable over the three years," Suor said.

Such instability reflects a general breakdown of the family's ability to provide a predictable and stable environment for the child.

"There are other environmental and biological factors that might contribute to children's lower cognitive functioning. However, our research, as well as previous studies, has indicated that cortisol plays a role in cognitive functioning," Suor added.

The findings are detailed in the journal Child Development.