Neurodevelopmental Disorders or Early Death in Siblings of Children With Cerebral Palsy

OBJECTIVES: To explore the presence of shared underlying causes of cerebral palsy (CP) and other neurodevelopmental disorders, by examining risks of other disorders in siblings of children with CP. METHODS: We used Norwegian national registries to identify 1.4 million pairs of full siblings (singletons) and 28 000 sets of twins born from 1967 to 2006, identify stillbirths and neonatal deaths, and find individuals with CP, epilepsy, intellectual disability, autism spectrum disorders, attention-deficit/hyperactivity disorder, blindness, deafness, schizophrenia, and bipolar disorder. Associations between CP in 1 sibling and neurodevelopmental disorders or early death in other siblings were estimated using logistic regression models. RESULTS: There were 5707 neonatal survivors (beyond 28 days) with CP (2.5/1000). These children had substantial comorbidity (eg, 29% had epilepsy). Singleton siblings of (singleton) children with CP had increased risks of neurodevelopmental problems, including epilepsy (odds ratio [OR], 1.8 [95% confidence interval (CI), 1.5–2.5]), intellectual disability (OR, 2.3 [95% CI, 1.8–2.9]), autism spectrum disorders (OR, 1.6 [95% CI, 1.1–2.2]), attention-deficit/hyperactivity disorder (OR 1.3 [95% CI, 1.1–1.6]), blindness (OR 2.4 [95% CI, 1.1–5.4]), and schizophrenia (OR 2.0 [95% CI, 1.2–3.2]). There was no increase in risk of bipolar disorder (OR 1.0 [95% CI, 0.6–1.6]). Families with children with CP also had increased risk of losing another child in the perinatal period (stillbirth OR, 1.8 [95% CI, 1.5– 2.3]; neonatal death OR, 1.7 [95% CI, 1.3–2.2]). Associations were stronger within sets of twins. CONCLUSIONS: Siblings of a child with CP were at increased risk for a variety of other neurodevelopmental morbidities, as well as early death, indicating the presence of shared underlying causes.