Compensatory and impaired trust updating in mild cognitive impairment: Evidence from computational modeling and fMRI.

Trust dynamics, how trust is formed, maintained, and adjusted, are essential to interpersonal functioning. Older adults with mild cognitive impairment (MCI) are known to exhibit social vulnerabilities, but the dynamic updating of trust during social interactions and its neural basis in this population remain unclear. Here, we combined computational modeling with task-based functional magnetic resonance imaging (fMRI) to investigate trust updating in 39 older adults with MCI (mean age = 67.8 years) compared to 45 normal healthy controls (NHC, mean age = 67.2 years). At the behavioral level, MCI participants showed slower trust reduction, larger prediction errors (PE), lower learning rates, and greater interference when interacting with non-cooperative partners, while responding similarly to cooperative ones compared to NHC. At the neural level, fMRI analyses revealed that, relative to the NHC group, MCI participants exhibited compensatory recruitment of central executive and default mode network regions during cooperative interactions. Conversely, during non-cooperative interactions, the MCI group showed reduced activation in social and executive cognition-related regions compared to controls. Critically, PE-modulated psychophysiological interaction analyses revealed diminished functional connectivity between the superior frontal gyrus and temporoparietal junction under non-cooperative conditions in the MCI group. Our findings suggest that while older adults with MCI can recruit compensatory neural resources during supportive interactions, they struggle to adaptively update trust when facing adverse social contexts. This impaired updating may underlie their heightened susceptibility to social exploitation and declining interpersonal functioning.