Age and intranasal oxytocin effects on trust-related decisions after breach of trust: Behavioral and brain evidence.

Age-related differences in cognition and socioemotional functions, and in associated brain regions, may reduce sensitivity to cues of untrustworthiness, with effects on trust-related decision making and trusting behavior. This study examined age-group differences in brain activity and behavior during a trust game. In this game, participants received "breach-of-trust" feedback after half of the trials. The feedback indicated that only 50% of the monetary investment into their fellow players had resulted in returns. The study also explored the effects of intranasal oxytocin on trust-related decisions in aging, based on suggestions of a modulatory role of oxytocin in response to negative social stimuli and perceptions of trust. Forty-seven younger and 46 older participants self-administered intranasal oxytocin or placebo, in a randomized, double-blind, between-subjects procedure, before they engaged in the trust game while undergoing functional magnetic resonance imaging (fMRI). Younger participants invested less into their game partners after breach-of-trust feedback, while older participants showed no significant difference in their investment after breach-of-trust feedback. Oxytocin did not modulate the behavioral effects. However, after breach-of-trust feedback, older participants in the oxytocin group showed less activity in the left superior temporal gyrus. In contrast, older participants in the placebo group showed more activity in left superior temporal gyrus after breach of trust. The findings may reflect reduced responsiveness to cues of untrustworthiness in older adults. Furthermore, the modulatory effect of oxytocin on left superior temporal gyrus activity among older adults supports the neuropeptide's age-differential role in neural processes in aging, including in the context of trust-related decision making. (PsycInfo Database Record (c) 2021 APA, all rights reserved).