Exploring links between type- and timing-specific characteristics of childhood maltreatment and epigenetic aging in formerly out-of-home placed young adults

Childhood maltreatment (CM) is a key risk factor for psychopathology, physical morbidity and premature mortality, potentially mediated by epigenetic processes like DNA methylation. While differential links between type and timing of CM and psychopathology are increasingly acknowledged, it remains unclear how type- and timing-specific characteristics of CM are associated with epigenetic measures of biological aging, including age acceleration, mortality risk, and the pace of aging. We thus aimed to explore these links in an at-risk sample of formerly out-of-home placed adults who often report significant exposure to CM and high rates of adverse health outcomes. One-hundred-sixteen young adults previously placed in youth residential care (33% women, age M = 26.3 years, SD = 3.6) completed the Maltreatment and Abuse Chronology of Exposure (MACE-X) and provided blood samples to estimate DNA methylation using the Illumina Infinium MethylationEPIC BeadChip Microarray. In preregistered analyses, conditional random forest regressions were used to estimate the importance of CM types (abuse, neglect, peer victimization, sexual abuse), timing (ages 3-18), and global measures (severity, multiplicity, duration) for the prediction of markers of epigenetic aging (Hannum’s and Pheno’s age acceleration and DunedinPACE). Abuse from age 9 until late adolescence predicted Hannum’s age acceleration more strongly than global CM measures and was consistently and negatively associated with it. BMI was positively linked to Hannum’s age acceleration. We found no association between CM and newer epigenetic clocks (i.e., Pheno’s age acceleration and DunedinPACE). In an at-risk sample of formerly out-of-home-placed young adults with high rates of CM, we provide first evidence that parental abuse from mid childhood until late adolescence – a potential sensitive period – was linked to decelerated epigenetic aging. CM should therefore be assessed dimensionally, rather than as a single, undifferentiated cumulative exposure.