Autism and other psychiatric comorbidity in neurofibromatosis type 1: evidence from a population‐based study

Aim To investigate psychopathology in children with neurofibromatosis type 1 (NF1), particularly the prevalence of autism spectrum disorder (ASD) and attention‐deficit–hyperactivity disorder (ADHD) symptomatology, using a population‐based sampling approach. Method Standard questionnaire screen reports were analysed for ASD (Social Responsiveness Scale, SRS), ADHD (Conners’ Parent Rating Scale‐ Revised, CPRS‐R), and other psychiatric morbidity (Strengths and Difficulties Questionnaire, SDQ) from parents and teachers of children aged from 4 to 16 years (112 females, 95 males) on the UK North West Regional Genetic Service register for NF1. Results Parental response rate was 52.7% (109/207 children; 59 females, 50 males, mean age 9y 11mo, SD 3y 3mo). The SRS showed that in 29.4% (32/109) of children, autism was in the severe, clinical range (T‐score>75) and in 26.6% (29/109) in the mild to moderate range (T‐score 60–75). CPRS‐R scores showed that in 53.8% (57/106) of children autism was in the clinical ADHD range (ADHD index T‐score>65). Based on their scores on the SDQ total difficulties scale, 41.5% (44/106) of children were in the abnormal range and 14.2% (15/106) were in the borderline range. Twenty‐five per cent (26/104) of children met criteria for both clinical autism and ADHD. Interpretation This representative population‐based sample of children with NF1 indicates a high prevalence of ASD symptoms associated with NF1 as well as substantial co‐occurrence with ADHD symptoms. The findings clarify the psychopathology of NF1 and show the disorder as a potentially important single‐gene cause for autism symptoms.