Associations between afternoon napping, left amygdala volume and cognitive performance in elderly with normal cognitive function

Background: The relationship between afternoon napping and cognitive function in the elderly is very complex and the mechanism is unknown.Methods: In the current study, 194 community elders with normal cognitive functions were included. All subjects completed baseline clinical assessment, baseline neuropsychological test as well as baseline structural MRI. Based on their napping status, these 194 participants were divided into the napping group (n = 88) and the nonnapping group (n = 106). We then compared the differences in cognitive performance and structural magnetic resonance between the two groups.Results: In the intergroup analysis, we found that the nappers showed poorer cognitive performance on both overall cognitive function and domain specific cognitive function; while on the whole sample, we found a significant negative association (F = 20.27, p<0.001) between afternoon napping and left amygdala volume. However, we did not find any effect of night sleep length or napping frequency on cognitive performance or left amygdala volume.Conclusions: In community elders with normal cognitive functions, afternoon napping is associated with cognitive performance, and left amygdala may play an important role in this process.