Exposure to maltreatment or trauma early in life is linked to lower IQ, research finds.
Being abused, physically or emotionally, neglected or witnessing domestic violence, was linked to an IQ score 7 points lower, on average.
Abuse that occurs before the age of two-years-old is particularly damaging to intellectual development.
The brain is very sensitive in this early period, neuroscience has revealed.
Trauma and adversity early in life has repeatedly been linked to changes in the structure and circuitry of the brain.
The conclusions come from a study of 206 US children enrolled in the Minnesota Longitudinal Study of Parents and Children.
The study started in 1975 and tracked the children from birth.
Children and mothers were assessed and interviewed at regular intervals and the children were given IQ tests.
The study revealed that one in three children had been maltreated and/or seen their mothers subject to violence.
This happened in infancy to 5 percent of children, in the pre-school period to 13 percent and in both periods to 19 percent.
Maltreatment — including witnessing violence and being neglected — was linked to lower intelligence scores every time it was measured.
The study’s authors write:
“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].
Because early brain organisation frames later neurological development, changes in early development may have lifelong consequences.”
The study was published in the Journal of Epidemiology & Community Health (Enlow et al., 2012).