Abstract
Changes in emotion recognition are observed in aging, in dementia, after brain lesions and as a function of mental health factors, such as depression. In aging, older adults have been argued to show a "positivity bias," which has been associated with a relatively spared recognition accuracy for positive emotion and an increased tendency to label emotions as positive. This bias has been suggested to support mental well-being. However, it has also been found in association with cognitive decline and brain lesions. Here, we investigated the behavioral and brain correlates of this age-related positivity bias. We used multimodal brain imaging in a large group of human adults (n = 665, 333 females) drawn from a population-derived cohort across the lifespan, together with a psychometric analysis of an emotion recognition task using facial expressions. Beyond reductions in expression recognition accuracy, older adults showed increased perceptual thresholds for negative emotions and a reduced threshold for the positive emotion, even after accounting for general face recognition abilities. This positivity bias in labeling emotions was strongly associated with lower cognitive performance in older people, but not with (nonclinical) depressive symptoms. It was also associated with reduced gray matter volume in the bilateral anterior hippocampus-amygdala and increased functional connectivity between these regions and the orbitofrontal cortex. Together, age-related positivity bias is associated with cognitive decline and structural and functional brain differences. A positivity bias in emotion recognition may therefore reflect an early marker of neurodegeneration, a hypothesis that could be tested in future longitudinal studies.