Background: Early parental death (EPD) is associated with adverse cognitive outcomes in later life. While prior research has examined demographic moderators like the gender of the deceased parent, the gender of the bereaved child, and the child's age at parental death, a gap remains regarding the potential moderating role of modifiable factors such as childhood social support (CSS).

Methods: This study included Black and White adults aged 45 and older from the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort study, who completed a Childhood and Family Life Questionnaire and underwent at least one cognitive assessment battery after enrollment. Participants with incident cognitive impairment or stroke before the assessment of the retrospective childhood variables were excluded. Linear mixed-effects models were used to examine the association between EPD and both average cognitive scores and longitudinal cognitive changes while controlling for age, education, race, sex, and childhood socioeconomic status. Moderating effects of CSS were tested using interaction and simple main effect analyses.

Results: Among 9,901 participants (mean age 63.06, men 43.20%, Blacks 26.90%) with follow-up through 09/2023, EPD was associated with lower performance on animal fluency (b= -0.34, p< .01), letter fluency (b= -0.21, p< .05), immediate recall (b= -0.21, p< .05), and delayed recall (b= -0.08, p< .05). EPD and CSS interactions were marginal. Simple main effect analyses revealed EPD was associated with lower Animal Fluency (b= -0.67, p< .01) and Immediate Recall (b= -0.50, p< .01) only among adults with high CSS. EPD was not associated with longitudinal cognitive change.

Conclusion: EPD is significantly associated with lower later-life cognitive functioning, but not the rate of cognitive decline. The findings provide some evidence of a protective role of CSS. Specifically, the findings suggest that the negative influence of EPD on later-life cognition may stem from the loss of a highly supportive parent, and that maintaining high levels of CSS following EPD can mitigate this negative impact. These findings provide a potential avenue for early intervention. Future research should investigate the underlying mechanisms through which EPD influences later-life cognitive health and how CSS provides a protective effect.