Exploring co-occurrence of sensory, motor and neurodevelopmental problems and epilepsy in children with severe-profound intellectual disability

BACKGROUND: Severe to profound intellectual disability (SPID) is associated with multiple neurodevelopmental disorders and problems. In the most severe cases, the term profound intellectual and multiple disabilities (PIMD) is used. This study aimed to explore the co-occurring disorders and neurodevelopmental problems in a sample of twins where the proband had SPID. METHOD: Within a population-based sample of (30 312) twins, 20 individuals with a national patient register SPID diagnosis were identified. Parent telephone interview data (screening of neurodevelopmental disorders) and register data (APGAR, birth weight, intellectual disabilities, epilepsy, motor and sensory disorders) were gathered for probands and co-twins. RESULTS: The 20 individuals with SPID all had between one and five additional disorders or problems, with autistic traits, motor problems and epilepsy being the most common. Clear discordance was found for ID and all additional disorders and problems between probands with SPID and their non-SPID co-twins. CONCLUSION: Children with SPID almost never present without neurodevelopmental and/or sensory and/or motor comorbidities. This heterogeneity should be reflected in clinical routine and in research targeting individuals with SPID. The results support a previously suggested conceptualization of a S/PIMD "spectrum". Autism may be considered for inclusion in future elaborations of such a S/PIMD spectrum.