Developmental trajectories in infants and pre-school children with Neurofibromatosis 1

Objective This prospective cohort study examines the cognitive, behavioural, ADHD trait and autism symptom development in infant and pre-school children with Neurofibromatosis 1 (NF1) compared with typically developing (TD) children without a family history of neurodevelopmental conditions. Methods Data from standardised tests was gathered at 5, 10, 14, 24 and 36 months of age (NF1 n=35, TD n=29). Developmental trajectories of cognitive and adaptive behavioural development from 5 to 36 months were analysed using linear mixed modelling. Measures of ADHD and autism traits were assessed at 24 and 36 months. Results The developmental trajectory of cognitive skills (all domains of the Mullen Scales of Early Learning -MSEL) and behavioural skills (four domains of the Vineland Adaptive Behaviour Scale -VABS) differed significantly between NF1 and TD groups. Post-hoc tests demonstrated that the NF1 participants scored significantly lower than TD participants at 24 months on all MSEL and VABS domains. The NF1 cohort demonstrated higher mean autism and ADHD traits at 24 months and 14% of the NF1 cohort met a research diagnostic classification for autism at 36 months. Conclusion By 24 months of age, the NF1 cohort show lower cognitive skills and adaptive behaviour and higher levels of autism and ADHD traits as compared to TD children.