Facial expression in mild dementia of the Alzheimer type

Abstract

Although the cognitive deficits in dementia of the Alzheimer type (DAT) have been extensively researched, much less is known about the emotional changes that may occur with this disease. The purpose of this investigation was to examine facial expression in response to emotional stimuli, and its relationship to subjective experience, in individuals with mild DAT. It was hypothesized that DAT would produce a decrease in cognitive control over emotional processes and facial expression, resulting in an increased tendency to mimic the facial expressions of others. DAT (n = 13) and age-matched control subjects (n = 21) viewed a series of 36 10 s video clips that varied according to emotion (happy/positive, sad/negative or neutral), presence of facial cues and presence of sound. They rated their levels of happiness and sadness after each vignette. Participants were videotaped while watching the vignettes, and the tapes were scored using the Facial Action Coding System (FACS). The DAT group showed more facial expression associated with negative affect in reaction to the sad vignettes than the control group, as well as a disproportionate effect of facial cues for the sad vignettes, suggesting reduced control of negative expression. Self-ratings of emotional experience were similar for both groups. Correlations between emotion ratings and intensity of facial expression were higher for controls than for the DAT group for happy vignettes, and were negligible for both groups for the sad vignettes. The results suggest that cognitive control over facial expression may be reduced early in the course of DAT.