Childhood intelligence predicts hospitalization with personality disorder in adulthood: evidence from a population-based study in Sweden.

Although low pre-morbid IQ is an established risk factor for severe mental illness, its association with personality disorder (PD) is unclear. We set out to examine whether there is a prospective association between childhood intelligence and PD in adulthood. Using a population-based prospective cohort study, we linked childhood IQ scores to routinely collected hospital discharge records in adulthood. Lower IQ scores were related to higher risk of being hospitalized with a PD across the full range of IQ scores, (odds ratio per one SD increase in IQ was 0.60; 95% CI: 0.49-0.75; p(trend) = 0.001). Adjusting for potential confounding variables had virtually no impact. We conclude that low childhood IQ predicts hospitalization with PD and may be an important factor in the development of PD.