Early life adversity is associated with phenotypic age but not delay discounting in chronologically young people

Early life adversity results in accelerated ageing, which has been detected using molecular markers of ageing such as telomere length and DNA methylation, even in chronologically young people. Further, animal models have shown that accelerated ageing leads to a decreased willingness to wait for delayed rewards. Our study aimed to develop a simpler and cheaper marker of phenotypic age, to investigate links between early-life adversity, ageing and delay discounting. In 250 UK younger adults (ages 17-38, 121 females, 129 males), we measured early life adversity, assessed phenotypic age using 9 markers of ageing and physical function, and took two measures of delay discounting (hypothetical and experiential). As expected, lower childhood socioeconomic status was associated with greater phenotypic age for chronological age. Participants of lower childhood socioeconomic status, and those with higher childhood trauma scores had poorer self-rated health and believed that they were more likely to experience premature death. Greater phenotypic age predicted worse self-rated health and lower perceived survival odds and mediated the association between childhood socioeconomic status and self-rated health. Contrary to our predictions, there were no associations between either early life adversity or phenotypic age and delay discounting. Neither was self-rated health associated with delay discounting. Better perceived survival odds, however, predicted greater hypothetical delay discounting. These findings demonstrate that accelerated ageing can be detected in chronologically young people, using non-invasive low-cost phenotypic age markers. The young adults in our sample who reported greater childhood adversity were not only aged according to our compound phenotypic marker, but also rated their own health as being poorer and believed that they were more likely to experience premature death. This suggests that people may have an awareness of their physical state, which they may use to inform their estimates of their own survival odds. However, our results did not support our predictions regarding the antecedents of delay discounting