FRIDAY, April 6, 2012 (HealthDay News) -- Suffering emotional trauma such as witnessing domestic violence or being abused early in life may inhibit children's intellectual development, according to a new study.
The researchers also found that the impact of trauma seems to be most damaging when it occurs during the first two years of life.
The U.S. study included 206 children whose intellectual development was assessed when they were aged 2, about 5 and 8 years old. The researchers also determined whether children suffered neglect; physical, sexual or emotional abuse; or witnessed domestic violence against their mother.
More than one in three (37 percent) of the children had suffered abuse or witnessed violence by about age 5. This occurred before age 2 in about 5 percent of children, during preschool (24 to 64 months) in 13 percent of children and during both periods in 19 percent of the children.
Children who suffered abuse or witnessed violence against their mother had lower-than-normal scores on tests of intellectual development. Those who experienced this type of trauma during the first 2 years of life had the lowest scores.
"The results suggest that [maltreatment and witnessing domestic violence] in early childhood, particularly during the first two years, has significant and enduring effects on cognitive development, even after adjusting for [other risk factors]," wrote researchers led by Michelle Bosquet Enlow, at Children's Hospital Boston.
The study, which found an association between witnessing violence and IQ but did not prove cause-and-effect, was published online April 2 in the Journal of Epidemiology and Community Health.
Even after accounting for other factors that could influence IQ, such as socioeconomic status, mother's IQ and birth complications, children who had witnessed or experienced violence had IQ scores that were more than 7 points lower than kids not subjected to mistreatment.
The researchers noted that the brain develops most rapidly during the early years of a child's life.
"Because early brain organization frames later neurological development, changes in early development may have lifelong consequences," they wrote.
Zero to Three has more about early brain development.