BACKGROUND: While adverse childhood experiences (ACEs) such as abuse or neglect are linked to lifelong interpersonal challenges, it's uncertain whether individuals with ACEs can effectively draw on others for distress relief and whether neural dyadic processes in these exchanges are compromised. METHOD: To address this gap, here we examined interbrain coupling between 'targets' (adults with a varying history of ACEs) and 'regulators' (unacquainted individuals without a history of ACEs) during two conditions: (i) distressing condition: where the target shares with the regulator a distressing biographical event
(ii) neutral condition: where the target shares with the regulator a neutral biographical event. After screening 534 participants, 58 dyads were simultaneously scanned with functional near-infrared spectroscopy (fNIRS), during the distress/neutral conditions to investigate interbrain coupling in the dorsolateral pre-frontal cortex (DLPFC), a core region of the emotion regulation network. RESULTS: Consistent with our hypothesis that individuals with high ACEs have difficulty relying on social support, we observed a significant negative relationship between targets' cumulative ACEs and distress relief during the distressing condition. Neuroimaging revealed that higher ACEs scores were significantly linked to differential interbrain coupling patterns in the DLPFC: increased coupling during the distressing condition and decreased coupling during the neutral condition. CONCLUSIONS: Among higher ACEs dyads, hyper interbrain coupling during distress may suggest heightened yet unsuccessful efforts to regulate distress, while hypo interbrain coupling in non-distressing situations may indicate poor connectedness in neutral social interactions. Therefore, abnormal interbrain coupling may underlie the difficulties high ACEs individuals face in benefiting from supportive interactions.