Alvarado, C.; Panlilio, C. C.; Perez-Edgar, K.; Thompsom, K. I.; Schaedig, D.; Melhem, N.; Perlman, S. B.

Interparental conflict and parental stress are well-established risk factors for child psychopathology, including elevated internalizing and externalizing symptoms. From a family systems framework, these stressors may spill over into the parent-child relationship, undermining emotional attachment and co-regulation processes central to children\'s mental health. Neural synchrony, defined as the dynamic, mutual alignment of brain activity between a parent and child, offers a biological index of these dyadic processes. Using functional near-infrared spectroscopy, researchers have shown that greater neural synchrony (NS) in prefrontal brain regions is associated with more attuned caregiving and positive child adjustment. Yet, NS is not uniform; it varies across dyads in pattern and regional distribution, potentially reflecting differences in relational dynamics, regulation, or stress exposure. To capture this heterogeneity, we used latent profile analysis to identify distinct synchrony patterns along the right and left ventrolateral and dorsolateral prefrontal cortices during the DB-DOS:Biosynch - a mild stress, three-context task. We further examined whether interparental conflict and perceived parental stress predicted profile membership, and whether children\'s internalizing and externalizing behaviors differed by profile. Among 194 dyads, two profiles emerged: lower baseline synchrony (LB; n = 132) and higher baseline synchrony (HB; n = 62). Greater interparental conflict reduced the odds of membership in HB, while parental stress was not predictive of profile membership. Additionally, children in LB exhibited higher levels of internalizing behaviors compared to HB, with no group differences observed for externalizing behaviors. These findings underscore the value of capturing synchrony heterogeneity in understanding family stress and child psychopathology.