A Pilot Trial of Dopamine Replacement for Dynamic Facial Expressions in Parkinson's Disease

Abstract

Background Current conflict exists regarding the potential beneficial effects of dopamine medications on facial expressivity in Parkinson's disease. Via digital video analysis software, we previously found reduced facial movement (entropy) and slower time to reach peak entropy in individuals with Parkinson's disease compared to controls. Objectives We aimed to determine whether levodopa medications improved parameters of dynamic facial expressions (amplitude, speed). Methods A total of 34 individuals with idiopathic Parkinson's disease were videotaped making voluntary facial expressions (happy, fear, anger, disgust) when “on” and “off” levodopa. Participants were 52 to 80 years old, early to mid‐stage disease, non‐demented, and included more men (65%). Expressions were digitized and analyzed using software that extracted three variables: two indices of movement change (total entropy, percent entropy change) and time to reach peak expression. Results Indices of facial movement (total entropy, peak entropy) and timing were significantly improved when patients were “on” vs “off” medication (all F's ≥ 3.00, P < 0.05). For total movement and time to reach peak entropy, levodopa‐related improvements were emotion nonspecific. Levodopa‐related improvement for peak entropy was driven primarily by happy expressions. There was no relationship between quantitative indices and clinical measures of mood (depression, anxiety) and motor disease severity. Conclusion The effects of levodopa on Parkinson's disease voluntary facial movement and on timing were robust and consistent with those of levodopa on other intentional movements in Parkinson's disease. This improvement possibly occurred because of levodopa enhanced activation of face representation areas in fronto‐cortical regions or because of less movement‐based suppression.

The Story behind the Mask: A Narrative Review on Hypomimia in Parkinson’s Disease

“…Under these conditions, hypomimia scores were significantly lower in ON condition than in OFF. Finally, a recent study testing dynamic facial expression, measured through an entropy video analysis of facial movement, showed greater facial movements in ON compared with OFF condition [58]. All these findings suggest a potential beneficial effect of dopaminergic treatment on hypomimia in PD patients.…”

“…This association has been investigated in other studies reporting correlations between hypomimia severity and bradykinesia, rigidity, and axial symptoms [51][52][53][54], suggesting a prominent role of dopaminergic system derangement in the genesis of hypomimia. Indeed, hypomimia severity has been recently associated with the level of nigrostriatal dopaminergic degeneration [55,56], and some studies reported the improvement of facial movement after L-DOPA administration [51,52,57,58]. Interestingly, hypomimia seems to improve during sleep [59].…”

“…In most published studies, hypomimia in PD patients was evaluated through the UPDRS or the MDS-UPDRS [52,53,55,56,58,71,73,97,[101][102][103][104][105]. However, it must be noted that such assessment suffers from subjective evaluation by the assessor and from the bias of high inter-and intra-rater variability.…”

“…Bowers and colleagues developed an index based on the entropy of sequential images converted in grey scale [123], which was used by other authors as well [90]. More recently, the former group applied the same methodology to quantify the effects of levodopa on facial expressions [58]. Eventually, other authors used the extraction of geometric features from images of emotions in PD to quantify hypomimia [124] and create new indexes of impairment [125] also from images captured via smartphones [104].…”

“…Taken together, these observations provided the rationale for dopaminergic treatment of hypomimia in PD patients. Only a few studies explored this aspect; hence, levodopa demonstrated some efficacy in ameliorating facial mobility [51,52,57,58]. Thus, PD patients displayed more marked reduction in pain expression, as assessed through videotapes during pain stimulation (Priebe et al, 2015), and more marked perioral stiffness [51] in OFF compared with ON state.…”