Background: The literature is mixed as to the relationship between intelligence quotient (IQ) and Posttraumatic Stress Disorder (PTSD) symptomatology in adult populations. Even less is known about the relationship in children who have been traumatized.
Methods: Fifty-nine children and adolescents (mean age = 10.6) with a history of interpersonal violence were evaluated with respect to PTSD symptomatology, number of traumas, and estimated Verbal, Performance and Full scale IQ scores. PTSD symptomatology included symptom levels for cluster B (re-experiencing), cluster C (avoidance and numbing), and cluster D (Hypervigilance) and criterion F, functional impairment.
Results: Results indicated that Full scale and Verbal IQ were significantly associated with the number of traumas, re-experiencing symptoms, and impairment. Performance IQ was only associated with impairment. Regression analyses suggested that together PTSD symptomatology predicted Full scale and Verbal IQ but nor Performance IQ and impairment was the single best predictor of IQ generally.
Conclusions: Findings provide support for an association between PTSD symptoms and IQ, particularly verbal IQ. Two possible reasons for this relationship are that higher levels of Verbal IQ may serve as a premorbid protective factor against the development of re-experiencing symptoms, or performance on post-trauma Verbal IQ measures may be negatively impacted by expression of PTSD symptoms. Longitudinal studies are needed to clarify which of these two possibilities explains the association.