RESEARKA

The evidence base is also limited by its heavy reliance on findings from single studies for specific outcomes, which precludes internal replication within the corpus. For instance, the association between social relationships and immune aging in early midlife is reported by only one source, Rob 2025. Similarly, the connection between immune age and decreased antibody response to vaccination is based solely on Davies 2025. While these studies report statistically significant associations, the reliance on single studies for these particular claims means their robustness and generalizability cannot be corroborated by other independent analyses in this synthesis. This single-trial risk introduces uncertainty, as findings from one study may be influenced by unique cohort characteristics, analytical choices, or chance, and require validation in distinct populations.

Citation Support

• source_1 Jongsma 2023
• source_2 Xie 2025
• source_3 Wallen 2024
• source_4 Hoang 2025
• source_5 Boudhabhay 2026