The Linear and Nonlinear Associations between Multiple Types of Trauma and IQ Discrepancy Indexes in African American and Iraqi Refugee Adolescents

Extreme stress resulting from various types of trauma is associated with changes in some brain structures that may affect IQ parameters. To assess relationships between multiple types of trauma and traumas, 390 African Americans and Iraqi refugee adolescents were studied. Nonlinear relationship between severe abuse, abandonment, parents divorce, age when adopted, witnessing domestic violence, and decreased verbal IQ, and between frequency of being in foster care, age when experienced death of close relative, and decreased perceptual IQ was found. Additionally, nonlinear relationships between extreme stresses resulting from such traumas and IQ discrepancy indexes were found.