Parental age at birth, telomere length, and autism spectrum disorders in the UK Biobank cohort.

Older parental age at birth is associated with increased risk of autism spectrum disorders (ASD) in offspring. Independently, shorter telomere length (TL) has also been shown to be associated with ASD in children. However, older paternal age at birth, with or without controlling for maternal age, has been associated with longer TL, a seemingly contradictory finding. Here, we conducted a retrospective cohort study among participants in the UK Biobank to disentangle associations between leukocyte TL and ASD status in adults, and the potential moderation by parental age on adult offspring's TL. Participants with ASD diagnosis (N = 87) with a mean age of 46.0 (SD 4.4) years were matched to participants without ASD diagnosis (N = 870) based on age, sex, ethnicity, education, household income, and assessment center. No statistically significant differences were seen in TL between participants with and without ASD when parental age at birth was not considered. However, there was a significant interaction between ASD diagnostic status and parental age on participants' TL, such that older paternal or maternal age at birth was more strongly associated with longer TL in participants with ASD. This study suggests that the shortened TL observed in children with ASD in previous research may partially depend on parental age at birth. Future studies tracking TL attrition before ASD diagnosis are warranted to depict temporal associations and the interacting effects of parental age at birth and ASD status on TL across the lifespan.