Mentalizing and Attachment From Infancy to Young Adulthood: Insights From the Metera Adoption Study

Mentalizing is a socio-cognitive capacity that develops within early attachment relationships, but institutional care may disrupt this process. Although adoption significantly improves developmental outcomes, it remains unclear whether socio-cognitive vulnerabilities observed in children persist in adulthood. This preregistered study aimed to explore (a) socio-cognitive catch-up in adult adoptees, and (b) predictors of reflective functioning (RF) in adulthood with a particular focus on attachment and interpersonal trust. Sixty-eight individuals were followed from infancy to adulthood. Adoptees did not differ from nonadoptees in RF in adulthood (Cohen's d = 0.07, 95% CI [-0.43, 0.57]), and age at adoption was not associated with RF (r = 0.02, p = 0.917). Cross-sectionally, RF was significantly correlated with dismissing (r = -0.58, p < 0.001) and preoccupied states of mind (r = 0.29, p = 0.017). Attachment in infancy (strange situation), preschool (attachment story completion task), and adolescence (child attachment interview) did not predict RF in adulthood. Interpersonal trust in adolescent and adult friendships was not associated with RF in adulthood. Overall, the findings suggest recovery in socio-cognitive development among adoptees with early institutional care and indicate that early attachment may not linearly predict RF. Future research should further explore developmental pathways to better understand the precursors of mentalizing in adulthood.