Perception of facial expressions of emotion in Parkinson's disease

[Truncated abstract] Perceiving facial expressions of emotion to infer the emotional states of others is central to the regulation of individual and social behavior. Results from individual studies on whether those with Parkinson’s disease (PD) are impaired in perceiving facial expressions of emotion are mixed. Despite these mixed results, a recent meta-analysis (Gray & Tickle-Degnen, 2010) showed an overall averaged medium-sized impairment for all of the so-called “basic emotions”. Most of the individual studies that were included in this meta-analysis required participants to identify facial expressions of emotion by name and sampled only expressions of emotion that were of full-blown intensity. The ability to discriminate emotional expressions of graded intensity from neutral expressions and the ability to discriminate graded intensities of the same emotional expressions is unexplored in PD.

The determinants of impaired perception of facial expressions of emotion in PD are unknown. The results from the Gray and Tickle-Degnen meta-analysis (2010) indicated that perception of emotional expressions in PD was unrelated to depressive symptoms, medication status, disease progression, and perception of visual form. The studies reviewed by Gray and Tickle-Degnen (2010) measured perception of visual form with the Benton Face Recognition Test (BFRT; Benton, Sivan, Hamsher, Varney, & Spreen, 1994) or a similar test, all of which are traditionally regarded as measures of face recognition. Although the BFRT might tap the ability to perceive visual form, it has been shown to be sensitive only to large impairments in facial identity recognition (Duchaine & Weidenfeld, 2003). The studies in the meta-analysis measured disease severity with the Hoehn and Yahr Staging Scale (Hoehn & Yahr, 1967), which has also been criticized as insensitive (Goetz et al., 2004).