Risk factors for intellectual disability in children with spastic cerebral palsy

Background: Cerebral Palsy (CP) is a non-progressive disorder of posture and movement caused by pre- or peri-natal lesions of the brain. Children with CP are also at increased risk for other disabilities, e.g. intellectual disability. Previous studies suggest the risk of intellectual disability varies in complex ways according to the type of motor impairment and perinatal factors such as gestational age. Objective: To determine patterns of risk for intellectual disability in children with spastic cerebral palsy (CP). Design: Cross-sectional, population-based study using the Northern Ireland Cerebral Palsy Register. Participants: Persons born 1981 – 2008 with congenital bilateral or unilateral spastic CP (n=1452). Outcome measure: Severe intellectual disability (IQ<50), as reported by clinicians known to the child. Data pertaining to CP subtype, sex, gestational age, birthweight and functional level were included in analyses. Results: Severe intellectual disability was significantly more prevalent in children with bilateral spastic CP (BSCP) compared to children with unilateral spastic CP (χ² (2) = 162.60, p < 0.001). Compared to very preterm infants with BSCP, risk for intellectual disability increased in moderately preterm (OR=3.97, 95% CI 1.04 to 15.23) and at-term children with BSCP (OR=2.51, 95% CI = 1.16 to 5.44). Conclusions: Children with BSCP are at increased risk of intellectual disability, with those born at term at the highest risk. The findings highlight the importance of early screening, particularly for children with BSCP born at term.