Recognition of disgust is selectively preserved in Alzheimer's disease

The neural substrates that subserve decoding of different emotional expressions are subject to different rates of degeneration and atrophy in Alzheimer's disease (AD), and there is therefore reason to anticipate that a differentiated profile of affect recognition impairment may emerge. However, it remains unclear whether AD differentially affects the recognition of specific emotions. Further, there is only limited research focused on whether affect recognition deficits in AD generalize to more ecologically valid stimuli. In the present study, relatively mild AD participants (n=24), older controls (n=30) and younger controls (n=30) were administered measures of affect recognition. Significant AD deficits were observed relative to both the younger and older control groups on a measure that involved labeling of static images of facial affect. AD deficits on this measure were observed in relation to all emotions assessed (anger, sadness, happiness, surprise and fear), with the exception of disgust, which was preserved even relative to the younger adult group. The relative preservation of disgust could not be attributed to biases in the choice of labels made, and it is suggested instead that this finding might reflect the relative sparing of the basal ganglia in AD. No significant AD effect was observed for the more ecologically valid measure that involved dynamic displays of facial expressions, in conjunction with paralinguistic and body movement cues, although a trend for greater AD difficulty was observed.