The interplay between biological aging and volunteering engagement in predicting cognitive performance: Evidence from the Harmonized Cognitive Assessment Protocol study

Background Promoting cognitive health and preventing deficits is crucial for improving the population level health and reducing economic burdens. Biological aging, influenced by DNA methylation (DNAm), plays a key role in predicting cognitive performance and brain aging. A more recent body of literature shows that social engagement, and volunteering in particular, may play an important role in modifying the relationship between epigenetic age acceleration and cognitive performance. Methods Using the Harmonized Cognitive Assessment Protocol in the Health and Retirement Study, the current project tests the association between five epigenetic clocks (Horvath, Hannum, PhenoAge, GrimAge, DunedinPoAm) and cognitive performance. It also examines whether the relationship between epigenetic clocks and cognitive performance differs by volunteering frequency (i.e., effect modification). Results Any level of volunteering was associated with better cognitive performance when compared to no volunteering. All DNAm clocks were associated with cognitive performance, except for PhenoAge. Evidence of effect modification was present for Horvath, PhenoAge, GrimAge, and DunedinPoAm. For PhenoAge and GrimAge, 1-100 hours of volunteering per year mitigated the influenced of accelerated biological age on cognitive performance. For Horvath and DunedinPoAm, the links between epigenetic age acceleration and cognitive performance were less steep for highly engaged volunteers (101+ hours per year). Conclusions The findings underscore the cognitive benefits of engagement in volunteer activities. They further elucidate the interplay between volunteering frequency and epigenetic aging on cognitive performance. The relationship between epigenetic age and cognitive performance also varies based on the level of volunteering engagement.