A study into the neurodevelopment of twins

Researchers asked caregivers of 3- to 18-year-old twins who were born preterm to complete an online survey about their twins' neurodevelopment. The study included 698 children (349 pairs of twins) and researchers investigated whether the traits parents observed were different between monozygotic (identical) and dizygotic (non-identical) twins and first- and second-born twins.

The findings of this study were an indication of the traits associated with autism, ADHD and anxiety, but importantly did not diagnose children with these conditions. Findings found that identical twins were more likely to show traits of inattention and social anxiety than non-identical twins. Researchers also found that twins who were born second compared with first were more likely to show traits of hyperactivity/impulsivity, autistic traits, social awareness differences, social cognition, social communication, restricted/repetitive behaviour, anxiety, generalised anxiety and social anxiety.

While these findings indicate that zygosity and birth order are important factors, further research is needed to look at long-term development and diagnosis.